True chameleons are not typical pets, and they are not for everyone. If you are thinking of getting a true chameleon, please think twice.
These animals are difficult to keep, even for experienced herpetologists. Prior to buying, please research your purchase carefully. Learn about the species, their needs, natural history. Then, if you still choose to buy, get your chameleon from a known, reputable breeder.
Be aware that caring for a chameleon is an expensive and time-consuming undertaking. Be sure you are prepared to make this sort of committment before getting a chameleon.