I have not yet bought a cham from a site sponsor, having always purchased my chams from pet stores (I'm out to 'save' them, one pet store at a time), but I would NOT recommend a pet store purchase as a first time cham buyer. I purchased a female panther from Pet Smart - after having been told it was a male, "sorry, we don't sell any female animals as we don't want them to become part of someone's breeding colony, we sell 'pets'" I have been told this twice, yet have come home with males that have turned out to be female. I don't mind, however if a store doesn't even know the gender of their pets, then they can't be trusted in their care of them. My last little veiled (who turned out, again to be female after I thought she was a he) also came home with pneumonia! She has survived her health scare but it did cost quite a bit in vet bills, which you wouldn't have if you bought from a site sponsor!!
Good luck!