That's a tough one, I can see where you feel you need to rescue this puppy but @ the same time, you're supporting this unethical breeder.
I would somehow try to get the puppy w/out paying the amount owed (like maybe mention the below law being broken)...& please get parvo vaccine right away (a pup as young as 6 weeks can get this shot). Call your vet ahead of time to make sure they have just the parvo shot for your pup bc they usu use the combo. Wrap your puppy in a blanket & don't let her touch the tables @ the vet's office, don't let her come in contact w/anything. Also get pet insurance that covers inherited diseases.
It is illegal in some states (including CA & Colorado) to sell under-aged puppies.
https://www.animallaw.info/statute/c...ities-act#s108
(k) To sell, transfer, or adopt dogs or cats under the age of eight weeks;