It's the rare breeder/seller who lets you come to their house or facility to pick up a critter. Usually they want to meet somewhere close by. If you are on-site then it's not rude to ask to see the parents.
No reputable breeder is going to have a problem with you doing a thorough inspection of the critter, including verifying the sex.
Cash is handed over once you are satisfied that the critter is healthy and as advertised.