just a suggestion when I receive deposits, I send a copy of my contract to the buyer via email download, I then request the buyer to sign it and return with their deposit, once paid in full they get the original signed with both mine and their signature, I keep a copy for my records. If you like read my contract it will give you some idea if your breeder doesnt have a contract ask them to write you one.
http://yorkiepassion.com/contract.htm
hope this helps