Aimee, PLEASE don't ever buy a puppy at a pet store! Try to boycott any pet store that sells puupies too! I won't buy anything from one that sells puppies!
That said, have you tried
www.puppymillrescue.com or
www.yorkshireterrierrescue.com? There are so many who need homes. I rescued my late Scruffy from a kill shelter years ago. In fact, someone from yorkietalk told me about him! He lived 5 years longer than the vet said he would!
Good luck on your search!
Elizabeth