I agree with Lynsey. Several things should happen before you are asked for a deposit. First of all, you should have been to see the pups and decided that they are strong and healthy. You should have satisfied yourself that the pups have been well-cared for and socialised. You should have seen at least the mother, and preferably the father as well, or some photos and details about the father if he is not owned by the breeders. If the breed is a pedigree, the breeder should have told you about the pedigree history. Even more importantly, the breeders should have been asking you all sorts of questions in order to satisfy themselves that you are a suitable prospective owner for one of their pups. And after all that, if both you and the breeder decide that buying a pup is right for you, THAT is when you should be asked for a deposit.

It sounds as though these breeders are not the kind of breeders you would want to buy a pup from - I would find a different breeder if I were you.