Cathi. if you are struggling to afford the initial cost of a Yorkie, this probably isn't a good time to get one. Dogs can be expensive to own, especially as they age. This is a good article that will give you an idea of the cost of owning a dog:
http://www.peteducation.com/article....articleid=1543
As a few others have mentioned, looking for a "bargain" puppy is a big mistake. Poorly bred Yorkies are less expensive, but can come with genetic time bombs just waiting to go off because their breeder didn't know about genetics and didn't do any health screening before breeding.
Why not start saving now for a wonderful Yorkie in the future when you are better prepared financially to afford it?