If your under 18 they would have said "little girl, we can't sell any animal to you unless your 18 or accompanied by an adult or legal guardian, sorry" and that's that and nothing else would have been said.
It's policy to take sick animals to the vet. Ever been in petco or the like and see the nasty ragged looking hamsters that they DON'T take to the vet....it's gross. Petsmart even adopts these sick hamsters out after they go to the vet if it's not something minor. If they didn't adopt these out then my GF wouldn't have 6 hamsters right now, and they would still be all stuck at Petsmart or worse. Seems minor I know, but if your the animal in question it's not. Just see it in our minds. If you want to bypass the system go in and buy some "pets". I understand snakes and other animals eat live....I get it. But Petsmart has the right to refuse any sell if they see fit. Policy is policy is policy, they are NOT going to bypass this. I would not go to that Petsmart again and call our corporate office and put in a complaint. They will do something about it, I promise you. The customers are the backbone of this business, we need you. Someone might not get fired, but will get talked to or written up or at the very least it will be on their record. They shouldn't have treated you like they did, call corporate.