deff DO NOT BUY IT FROM A PET STORE. they typically have NO IDEA what they are doing when it comes to chameleons. I've seen chameleon enclosures in Petco and Petsmart and their enclosures are VERY VERY bad. hardly anything to climb on, standing water in a bowl instead of a dripper (because chameleons don't usually like water bowls)..... the Petsmart down the street from me actually has a HUGE adult Veiled Chameleon in an enclosure that wouldn't even be big enough for a baby chameleon (the enclose is maybe 16 x 16 x 16 TOPS) and it doesn't even have a UVB on it.
very bad keeping there.
most (not all) pet stores also feed chameleons only mealworms, or at least they do in my experience. probably because they can be placed in a cup and it's easy. well, those are really not that good for a chameleon. in moderation they are okay... but as a staple diet? deff not.
it may cost a bit more to go through a breeder or get online from a breeder, but it will be worth it in the end. your chameleon will be ALOT better off if you go that route.