I'm glad Nancy outed that website. Mass production of puppies always causes red flags to come out.
I would suggest you go to the AKC website and look for a conformation or Yorkie breed club in an area that is close to you. The clubs have breeder referral people who will only refer you to approved breeders. They are very careful to only name good breeders as they need to protect their reputations.
American Kennel Club - Club Search and Directory
The standard weight for a Yorkie is 7lbs and under. If you buy from a breeder with a reputation for breeding a good consistent line of Yorkies you will have a much better chance of getting a pup that will be within the standard size.