First of alll....
It is truly an awesome place!
I believe that the cost of a yorkie depends upon a couple of things:
1) the amount of $$ a buyer is willing to spend for a pup
2) the amount of $$ a seller is requiring for the pup
Unfortunately the quality and health of the puppy is not always part of the those two things. That is why it is critical that when you get serious about purchasing a puppy, please do business with a reputable breeder.