I would be worried about getting a healthy yorkie more than worrying about their size. Have you even seen a 3-4 pound yorkie in person? When I went to see my breeder most of her adult yorkies were around 6 pounds and they were very very tiny. My gosh, smaller than a lot of human babies when born.
I would look for breeders that belong to YTCA and who follow their code of ethics.
Good luck finding your baby
