I would never buy a yorkie from a breeder who clearly is breeding tiny dogs.
This puppy sounds like she is off to a rough start......I would be VERY leery. The fact that breeder is selling a tiny 9 week old puppy is very telling about her breeding program.
The story about her stomach sounds weird to me. Never heard of such a thing. If you have deep pockets and can live with a horrible outcome, go for it. If not, then RUN away.
Puppyfind.com is not a place to look for a pup IMHO. I would suggest looking at the Yorkshire Terrier breed page .. they have a list of breeders. You can then look at the breeders first....then look for a puppy.
The Yorkshire Terrier Club of America