A disproportionate amount of my income goes to recreational gear. I'm a cycling enthusiast and thrive on the performance enhancements of new bike gear. It's mostly incremental gains, but you'll also get the occasional breakthrough.
A good travel backpack isn't going to be particularly couture; there will be no multitude of straps or attention-getting devices. It will be easy pack, easy to unpack, and not be murder on the shoulders or lower back.