I just recently got my first yorkie. For some reason they are very popular here in Missouri. There is a local pet store here in my town and about 4 women (all family) own it. They have been breeders of yorkies and shih-tzus for many many years now. I have always seen yorkies and shih-tzus at the shop here and there. Just last week one of the women had a little yorkie (he's part of our family now), and she was selling him for $399. She said the only reason she had him is because a woman had wanted him, but decided on a poodle instead. And she told me that the only reason she was selling him for $399 was because he was 2lbs. at 8 weeks and was going to be a larger yorkie (around 7-10 lbs.). The ones that are going to be smaller when they are older (around 4 lbs.) she sells for at least $1,000. I couldn't believe that. But that is kind of the demand for yorkies. The smaller the better. Personally I wanted a little bigger yorkie. I would be scared of something that small, especially with 3 kids. They also have a guaranty on there dogs and they are registered and she had him up to date on his shots and worming and the vet said he was doing great.
I wish you luck in finding your yorkie.