I know how you feel. My Maltese Lady is poorly bred and has so many health problems - epilepsy, diabetes, arthritis, hypothyroidism, allergies, plus chronic infections from the diabetes. "Bargain" puppies from backyard breeders are no bargain in the long run, are they?
I'd suggest sticking with a breeder recommended by the YTCA. They are required to follow the Code of Ethics and Conduct and health test, breed to the standard, etc.
Yorkshire Terrier Club of America About The Club