Medical marijuana dispensaries have attracted two predictable byproducts of the valuable buds sold in an increasing number of stores: thieves and security systems.

"There is a lot of smash and grab," Dan Williams, founder of Canna Security America, told CNN Money about pot-shop crime. Williams' Denver-based company specializes in providing security systems, including cameras and panic buttons, for medical marijuana stores.

It's not just the merchandise that's luring criminals. Pot shops tend to have bundles of cash on the premises, as unsympathetic federal laws have forced many stores to operate in hard currency, say security experts interviewed by CNN.

Small security companies, like Canna, have an opportunity to make money from the growing industry, as more established firms like ADT have pulled their services from some medical marijuana shops.

Contacted by The Huffington Post, an ADT spokeswoman said in a statement that the company does not work with businesses selling pot. “ADT has made a policy decision not to sell security services to businesses engaged in the marijuana industry because it is still illegal under federal law," the statement said.

Across the country, 18 states and the District of Columbia allow the production and use of marijuana for medical purposes. Two states, Colorado and Washington, also have approved it for recreational use.

An estimated 2,000 to 4,000 businesses now produce pot legally under state laws, The Wall Street Journal reported earlier this month. And it's big business: Total sales added up to well over $1 billion last year.

But even as the legal business has grown, there is still a healthy black market for marijuana, which sells for around $2,000 a pound wholesale, CNN reported.

Loading Slideshow...
  • $13.7 Billion Saved On Prohibition Enforcement Costs

    The government would save an estimated $13.7 billion on prohibition enforcement costs and tax revenue by legalizing marijuana, <a href="http://www.huffingtonpost.com/2012/04/17/economists-marijuana-legalization_n_1431840.html" target="_hplink">according to a paper endorsed by 300 economists</a>.

  • $500 Million In Tax Revenue For Washington State

    It's estimated that Washington's legalization of marijuana could bring the state an<a href="http://www.wptv.com/dpp/news/national/marijuana-legalization-decision-washington-colorado-oregon-can-pot-stimulate-the-economy" target="_hplink"> additional $500 million in tax revenue</a>, WPTV reports.

  • $60 Million Saved By Colorado Legalization

    Colorado's pot legalization legislation, Amendment 64, is estimated to create <a href="http://csbj.com/2012/11/02/marijuana-economic-stimulant-or-just-a-can-of-worms/" target="_hplink">$60 million for the state in combined savings and additional tax revenue</a>, Colorado Springs Business Journal reports.

  • Legalization Could Reduce Marijuana Prices

    Marijuana users could see substantial savings due to marijuana legalization, as <a href="http://www.huffingtonpost.com/2012/11/07/legalizing-marijuana-washington-colorado_n_2088375.html?1352310298" target="_hplink">prices could fall by up to 100 times</a>, perhaps freeing up some cash to spend on other things.

  • Huge Prison Cost Savings

    Inmates incarcerated on marijuana-related charges cost U.S. prisons $1 billion annually, according to a 2007 study, <a href="http://www.alternet.org/rights/47815/" target="_hplink">AlterNet reports</a>.

  • Marijuana Prohibition Costs Taxpayers $41.8 Billion A Year

    Including lost tax revenues, a 2007 study found that enforcing the marijuana prohibition costs tax payers $41.8 billion annually, <a href="http://www.forbes.com/2007/09/29/marijuana-laws-work-biz-cx_qh_1001pot.html" target="_hplink">Forbes</a> reports.

  • California Marijuana Crop Worth $14 Billion A Year

    Marijuana growers account for <a href="http://www.time.com/time/nation/article/0,8599,1884956,00.html" target="_hplink">$14 billion a year in sales in California</a>, making it the state's most valuable cash crop, TIME reports.

  • Illegal Marijuana A $36 Billion A Year Industry

    It's estimated that <a href="http://madamenoire.com/106691/capitalizing-on-the-billion-dollar-marijuana-industry/" target="_hplink">illegal marijuana is a $36 billion industry</a> in the U.S., MadameNoire reports.

  • Dispensary Ads Boost Newspapers' Revenue

    The <em>Sacramento News and Review</em> saw a big boost in ad revenue when it offered advertising space for more than 60 medical marijuana dispensaries, enabling the publication to hire three additional employees, <a href="http://www.news10.net/news/local/article/144285/2/Marijuana-ads-mean-big-money-for-weekly-newspaper" target="_hplink">according to News 10</a>.

  • Mendocino Zip Tie Program Raised $600,000

    Mendocino County, California's zip tie program aimed at regulating medical marijuana growing by charging permits for each plant raised <a href="http://www.huffingtonpost.com/2012/01/09/medical-marijuana-license-mendocino_n_1193198.html" target="_hplink">$600,000 in revenue in for the Sheriff's department</a> in 2011.

  • Oakland Raised More Than $1 Million In Marijuana Tax Revenue

    The city of Oakland, California raised $1.3 million in tax revenue from medical marijuana dispensaries in 2011, 3 percent of the city's total business tax revenue, according to <a href="http://www.nytimes.com/2012/02/12/us/cities-turn-to-a-crop-for-cash-medical-marijuana.html?_r=1" target="_hplink"><em>The New York Times</em></a>.

  • Colorado Pulls In $5 Million From Pot Sales Tax

    In 2011, Colorado pulled in $5 milllion in sales taxes from medical marijuana businesses, <a href="http://www.nytimes.com/2012/02/12/us/cities-turn-to-a-crop-for-cash-medical-marijuana.html?_r=1" target="_hplink"><em>The New York Times</em></a> reports.

  • Legal Marijuana Could Be $100 Billion Industry

    Economist Stephen Easton estimated in 2010 that <a href="http://www.businessweek.com/debateroom/archives/2010/03/legalize_mariju.html" target="_hplink">legal marijuana could be a $45 to $100 billion industry</a>, <em>Bloomberg Businessweek</em> reports.

  • Each weGrow Center Creates 75 Jobs

    When hydroponic marijuana growing supply chain weGrow opens a new store it <a href="http://aznow.biz/small-biz/wegrow-phoenix-opens-cultivates-opportunities-arizona)" target="_hplink">creates an estimated 75 jobs</a> indirectly, according to AZBusiness Magazine.