On Wednesday, September 12, at about 12:45 EST, two important, related things are going to happen:

1. Apple CEO Tim Cook will introduce the new iPhone.
2. The price that you can sell your old iPhone for will drop dramatically.

The second, of course, will occur because of the first -- once the "iPhone 5" becomes real, and not just an idea composed of an endless stream of rumors and supposed leaks, the resale value for all previous iPhone models will plummet. Everyone will want the New Hotness, and no one will want the Old and Busted, as they say.

Given this bit of information, then, let this serve as your final reminder: If you are planning to buy the new iPhone, and you want to get the most money possible back from your existing iPhone, you need to sell your current phone before Tim Cook's speech on Wednesday.

Back in August, we handed down a maxim to you that our great-grandparents handed down to us: "The earlier you sell your iPhone before an Apple event, the better." That was based on data from two different gadget resale websites, which showed sharp declines in the prices they can pay as an Apple event nears. Here, for example, is a chart of the value of different iPhones in the weeks leading up to the unveiling of the iPhone 4S, on the popular gadget trade-in site Gazelle:

iphone value

[UPDATE: We have a better chart from Gazelle, which shows prices in the days leading up to and after the announcement of the iPhone 4S].

The iPhone 4S was introduced on October 4: After a small spike in prices the following day -- probably due to the widespread initial disappointment that there was no redesign to the phone's body -- the value of an old iPhone steadily decreased over the following weeks. That decrease could be more pronounced this year, with a new design widely expected for the so-called "iPhone 5."

Selling your old iPhone -- rather than just letting it rot in a desk drawer -- can significantly defray the cost of your new purchase, especially if you have an iPhone 4S. On Gazelle, a 16GB iPhone in good condition fetches $277; on a similar site called NextWorth, $280. Both services work the same: You get a quote on your device, and then you have 30 days to mail in your gadget, postage paid by the sites. Once your gadget is received, the company mails you a check. That's a sizable chunk of change that can work toward undoing much of the upfront cost in buying a new smartphone.

There are other places that will buy your old iPhone, too. Apple itself, for example, lets you bring your phone to an Apple store and will repay you in store credit. More traditional consumer retail sites like eBay, Amazon, and Craigslist also function as active gadget marketplaces and can often bring higher prices than those at Gazelle, Nextworth, or Apple.

I recommend Gazelle or Nextworth, though, because of both the price certainty and that 30-day window: Those 30 days allow you to keep your current iPhone until you're able to purchase your new one, so that you don't have to go phone-less for a few weeks. Though the new iPhone will be unveiled on Wednesday, it likely won't be available for 10 days afterwards -- and even then, supplies will probably be limited. There's no guarantee you'll be able to get your hands on an iPhone 5 the day it comes out; the generous 30-day window should give you plenty of time to do so.

By all means, then: If you're cell phone contract is up, and you currently own an iPhone, now is the time to sell. When you wake up on Wednesday, your iPhone won't be worth as much as it was on Tuesday. Sell now, and sell fast, before the Hump Day takes a hunk of change out of your pocket.

Earlier on HuffPost:

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  • The iPhone 5 Will Finally -- FINALLY! -- Be Here On Wednesday

    Before we get started on this super-sized edition of <strong>This Week In Apple Rumors</strong>, I'd just like to say that this is, personally, a bittersweet column for me to write. You see, for about 14 months, I've been writing about a mysterious little bugger apparently being produced by Apple called "the iPhone 5." The details of the "iPhone 5" have shifted over time -- we've gone from a 4.8-inch screen, and a teardrop design inspired by the MacBook Air (at left), to the more conservative version that Apple is expected to introduce on Wednesday -- but it has always been the "iPhone 5," a name that is not what Apple is expected to call the next iPhone, but which has morphed into blogger shorthand for "new iPhone that doesn't look like current iPhone." For 14 months I've followed the development of the idea of the iPhone 5 -- how big the screen would be, when it would be released, what features it might add, whether it would revolutionize smartphones as we knew them -- and for 14 months, the iPhone 5 has remained just that: An idea. Not a thing to be released or held in anyone's hand or pocket, but an idea. And, well, it appears that now the "iPhone 5" is going to be unveiled, on Wednesday, September 12, at an Apple event in San Francisco. It's a bittersweet feeling, really, the feeling of a great release, the end of an enormous constipation, akin to graduating from college after years of work, or of finally passing a kidney stone. I've spent so much time on the iPhone 5, parsing endless webpages full of speculation, rumors, hypotheses, hunches, "leaks," and mock-ups (again, see a hilariously wrong one from early in the game at our left) that I can barely imagine what This Week In Apple Rumors will be like without an endless stream of nonsensical iPhone 5 chatter. For on Wednesday, the DiMaggio-esque streak of iPhone 5 appearances in this column will end. The iPhone 5 we've been lusting after for a year and a half will manifest itself; and so we'll come to the end of an era of sorts in Apple Rumorwatching. It will be a bittersweet day, for sure, but hey -- there's always the iPhone 6. I hear it's going to have rocket boosters. And now, without further ado: Let's get on to the rumors, starting with, as always the iPhone 5:

  • ATTN: New iPhone Incoming!

    The new iPhone, like Omar, is comin': It figures to be the star of the show when Tim Cook takes the stage in San Francisco at Apple's event on Wednesday, September 12. It should, by most accounts, go on sale nine days later, on Friday, September 21 (pre-orders, of course, will begin right after Cook is done talking in San Fran). My <a href="http://www.huffingtonpost.com/2012/09/05/iphone-5-rumors-what-we-think-we-know_n_1859295.html" target="_hplink">dashing colleague Tim Stenovec did a handy roundup</a> of everything we think we know about it, but to recap: A 4.0-inch screen; a smaller dock connector; a taller, thinner, lighter body; the headphone jack moved to the bottom; iOS 6; 4G LTE. Apple blog <a href="http://www.imore.com/" target="_hplink">iMore</a> -- which has really led the charge in accurate Apple rumors this cycle -- says that the leaks are correct, and that the next iPhone will indeed resemble the taller, slimmer model we've been seeing in all these leaks. (Just for good measure, here's another one on your left, <a href="http://www.iresq.com/" target="_hplink">freshly leaked this week by repair firm iResQ</a>, which shows how the new iPhone will compare to the iPhone 4S. You can sort of glimpse the bottom of the phone, too, with the smaler dock connector and new location for the headphone jack). <a href="http://www.anandtech.com/show/6196/preparing-for-the-iphone-next-rumors-analyzed/4" target="_hplink">AnandTech reported last week that</a> NFC capability for a mobile wallet feature would NOT be included, which <a href="http://www.loopinsight.com/2012/08/28/nfc-on-the-new-iphone/" target="_hplink">seems to be the consensus</a>; 9to5Mac is reporting (totally unsurprisingly) <a href="http://9to5mac.com/2012/09/07/redesigned-iphone-n42-being-announced-next-week-at-iphone-4s-price-points" target="_hplink">that the new iPhone will cost</a> the same amount of money as the iPhone 4S does (starting at $199 on contract for a 16GB version) which seems totally logical. It also seems like the iPhone 3GS is going to be put out to pasture: That curvy design of yore will disappear, as <a href="http://www.telegraph.co.uk/technology/apple/9525487/Apple-to-drop-iPhone-3GS.html" target="_hplink">Apple will make the iPhone 4 its free phone</a>. (For more on what the "iPhone 5" will probably look like: <a href="http://3dexport.com/3dmodel-iphone-5-prototype-55736.htm" target="_hplink">Martin Hajek has made the best, most accurate mock-ups</a> (we think), while <a href="http://www.gottabemobile.com/2012/09/03/iphone-5-video-rumors/" target="_hplink">this video shows</a> a dummy model that most think will resemble the real deal). And that's about all she wrote for the so-called "iPhone 5," which we're going to see for real-real on Wednesday. I know that "FINALLY" is completely overused at this point, but after something like two years of predictions of a redesign for the iPhone 4S, I feel justified in proclaiming: FINALLY!!!

  • New iPods To Share Stage With New iPhone

    Tim Cook isn't just going to introduce a new iPhone on Wednesday -- <a href="http://www.appleinsider.com/articles/12/08/31/iphone_5_ipad_mini_among_8_new_apple_products_coming_before_end_of_2012/" target="_hplink">KGI Securities analyst Ming-Chi Kuo has predicted</a> Apple will unveil 8 new products by the end of the year -- and we're hearing more and more about what those additional new products might be. <a href="http://9to5mac.com/2012/09/07/apples-new-ipods-various-new-ipod-touches-new-ipod-nano-tweaked-ipod-shuffle/" target="_hplink">9to5Mac's Mark Gurman has it on good authority that</a> an absolute boatload of new iPods will debut onstage. The Raymond Carver Short Story version is that Apple will be totally overhauling the design of the iPod Nano and the iPod Touch while lightly tweaking the iPod Shuffle. The Jonathan Franzen longer version -- if you're in the market for an iPod -- <a href="http://9to5mac.com/2012/09/07/apples-new-ipods-various-new-ipod-touches-new-ipod-nano-tweaked-ipod-shuffle/" target="_hplink">is available at 9to5Mac</a>, who has a bunch of details about the upcoming raft of new iPods. It's been a couple years since Apple has made any improvements or design changes for its iPod line, which was once the Cadillac (or Mercedes) of the company, and also the inspiration for some of the most inspired and zeitgeist-y commercials ever. Though the iPhone and iPad both come with MP3 players, the single-function iPods remain popular, and these design changes, if true, could re-inject some excitement around the devices.

  • Apple's New iMacs Will Also Be Unveiled Tuesday: Attractive Fox News Journalist

    <a href="http://www.foxnews.com/tech/2012/09/07/apple-to-unveil-new-lineup-imacs/" target="_hplink">Fox News correspondent and <a href="http://www.mediaite.com/power-grid/person/?q=Clayton+Morris" target="_hplink">Handsome Gentleman</a> Clayton Morris is reporting that</a>, in addition to the iPods and the iPhone, Tim Cook will also take the wraps off a bunch of new iMac all-in-one computers at the Wednesday event. Morris, who is just a really good-looking guy, isn't quite sure if these will be Retina iMacs, but <a href="http://www.foxnews.com/tech/2012/09/07/apple-to-unveil-new-lineup-imacs/" target="_hplink">he does say that</a> the new iMacs will come with the faster Ivy Bridge processors, SSD storage, USB 3.0, and an improved graphic chip. That Apple didn't update its iMac line at WWDC, when it majorly refreshed its MacBooks, was a bit surprising. But now, if Morris (whose face is really just aesthetically pleasing) is correct, we could be days away from improved iMacs. Ming-Chi Kuo, who is quite plugged into the Apple supply chain, and whose handsomeness I cannot confirm at this time, <a href="http://www.appleinsider.com/articles/12/08/31/apples_new_imac_expected_to_be_redesigned_without_retina_display.html" target="_hplink">seems to think that the Retina iMac will come next year</a>. Apple's event is starting to come into focus, as two well-connected individuals (Gurman of 9to5Mac and Morris of Fox News) have filled in some details: It's looking like the iMac and iPod will set the stage for the big iPhone 5 reveal. For more on what Morris hears about the new iMac, <a href="http://www.foxnews.com/tech/2012/09/07/apple-to-unveil-new-lineup-imacs/" target="_hplink">click here</a>; for photos of his almost overwhelmingly handsome face, with chiseled jaw, perfect hair, and brilliant smile, <a href="https://www.google.com/search?q=clayton+morris&sugexp=chrome,mod%3D19&um=1&ie=UTF-8&hl=en&tbm=isch&source=og&sa=N&tab=wi&authuser=0&ei=uGNKUP6gC4nv0gGj7IHABQ&biw=1378&bih=816&sei=vGNKUKTDAtPG0AHi9oDADw" target="_hplink">click here</a>.

  • Apple Trying To Build Its Own Pandora

    Curiouser and curiouser! This week a pair of reports -- from the <a href="http://professional.wsj.com/article/SB10000872396390443589304577636110080423398.html?mg=reno64-wsj" target="_hplink"><em>Wall Street Journal</em></a> and the <a href="http://www.nytimes.com/2012/09/07/technology/apple-plans-to-challenge-pandora-in-web-radio.html" target="_hplink"><em>New York Times</em></a> -- suggested that Apple was working on a Pandora-like app that would come pre-installed on iPhones and iPads and that would function as a kind of taste-based radio station, in the vein of Pandora and IHeartRadio. The service would be ad-supported, though users could remove ads by paying a yearly subscription fee. Why would Apple be interested in competing with Pandora. (Or, really, why wouldn't Apple just buy Pandora?) <a href="http://allthingsd.com/20120906/apple-wants-to-build-its-own-pandora-why/" target="_hplink">Peter Kafka of AllThingsD has a good explanation</a>: Apple thinks that it can use its cozy relationship with the labels to create a better experience for the user than what is offered on Pandora (think the ability to replay, select songs you actually want to hear, etc.). It is already a goliath in digital music, with iTunes being the largest music store in the world; its efforts to build a meaningful service on top of iTunes (Ping, iTunes Match) have thus far proved somewhat fruitless. Third time's a charm, <a href="http://en.wikipedia.org/wiki/Jane_Seymour" target="_hplink">unless you are Jane Seymour</a> or <em>The Godfather</em> franchise. No word on when Apple's Pandora might premiere, so Pandora employees need not start polishing their resumes quite yet.

  • No Apple Television In The Near Future, Alas

    With all of these Apple gadgets and radio stations and press events coming over the next few months, it's time to hold a moment of silence for one rumored iDevice that apparently won't rear its shiny white head in 2012: <a href="http://www.huffingtonpost.com/2012/09/06/apple-itv-2012_n_1861661.html" target="_hplink">The Apple television, or "iTV."</a> We know that Apple is working to magically revolutionize the television experience, because Steve Jobs said as much to his biographer. But <a href="http://www.bloomberg.com/news/2012-09-06/apple-tv-no-iphone-as-talks-bog-down-with-media-companies.html" target="_hplink">a fresh report from Bloomberg says</a> that Apple is not enjoying its talks with the cable companies, who are far more resistant to change than the struggling music labels were a decade ago. For now -- rather than a full-on television set -- Apple is working on a set-top box that would replace the box you lease from your cable company, according to Bloomberg; the box would allow you, with a cable subscription, to watch live TV, archived episodes of old shows, and Internet content, all on an interface designed by Apple. Problem is, cable companies pretty much don't like any of that: They don't want Apple to have total control over the interface; they don't want Apple to be able to sell the box directly to consumers; and the networks don't want to make all of their old content available to Apple for on-demand viewing. So, uh, what we have here is a failure to communicate or agree on basically any part of Apple's plan to revolutionize the television. Negotiations are, as ever, ongoing, but <a href="http://www.bloomberg.com/news/2012-09-06/apple-tv-no-iphone-as-talks-bog-down-with-media-companies.html" target="_hplink">Bloomberg warns</a> not to expect any real progress, or release of a final product, any time soon -- certainly not this year. Maybe next Christmas, little Johnny.

  • Lots Of iPad Mini Parts Keep Getting Photographed

    I don't know what kind of security measures they have at the plants manufacturing the iPad Mini -- you know, the smaller, cheaper iPad that is rumored for an October release -- but it would seem as though it's pretty easy for employees there to sneak out parts. Like, almost every week there are a bunch of new photos of iPad Mini parts, each more definitive than the last. This week there were two such leaks -- one, at left, from Chinese site tech.163.com, <a href="http://tech.163.com/digi/12/0905/14/8AL79DEM00161MAH.html" target="_hplink">is supposedly the casing</a> of the MiniPad: Tech.163 has a bunch of high-definition photos of the case, and the one at left shows how the iPad with the 7.6-inch screen might compare size-wise with its big brother. <a href="http://tech.163.com/digi/12/0905/14/8AL79DEM00161MAH.html" target="_hplink">You can head to the site for more</a>, including the backside of the case, with Apple logo. Meanwhile...

  • Yet More iPad Mini Parts!

    That last photo showed the iPad Mini casing next to an iPad; this one shows an iPad Mini mold next to iPhone 4S and comes from <a href="http://www.giga.de/" target="_hplink">Giga.de</a>. Good news for security guards in China looking for work: I'm guessing there will be a hiring spree in the coming days.

  • Also, Designers Really Like Making iPad Mini Mock-Ups

    When you've got all these parts leaking out, it makes it really easy for designers to make mock-ups based on the schematics and whatnot. MacRumors went ahead and commissioned this video, based on all the leaks of the past several weeks. Press play and prepare to say "Ooh" and "Aah." That's all for This Week In Apple Rumors. Make sure to check back next week, when we'll have all the information on the iPhone 6, iPhone 7, and, perhaps -- if you're really lucky -- iPhone 8, a 7G LTE device with a 92.7-inch screen weighing just 0.13 ounces. It's going to be something, and you won't want to miss it! And if you can't wait for your weekly dose of Apple rumors, remember that you can always get up-to-the-minute rumors by following me right <a href="http://twitter.com/gilbertjasono" target="_hplink">here</a>.