Have you tried the Yorkshire Terrier Club of America Breeder referral? Their breeders must adhere to their "code of ethics and conduct" to conform to the breed standard as approved by the American Kennel Club. I found my two yorkies through breeders in Connecticut and it was well worth the drive. There are several in the NY area. Here is the link:
http://www.ytca.org/breeder4.html#NY
Good luck!