Thanks for the info, everyone.

In both cases--in Springfield and St. Louis--the chameleons I saw were in tiny, less than five-gallon, glass cubicles near the center of the store. No reptarium, no ventilation and no written information other than provide high humidity and heat. Due respect, but I don't think a gecko, a relatively easy-to-care-for, hardy reptile, is an appropriate comparison with a Jackson's chameleon (google a care sheet for one and see what I mean). If it were within my means to properly care for a Jackson's chameleon, I'd buy one in a heartbeat because they're the prettiest lizard I've ever seen. After researching, however, I'm quite convinced I couldn't pull it off, nor could most folks--nor, judging by what I saw at these two stores, could Petsmart.