I agree with the above posts--there are too many yorkies that need rescuing. Please consider this option first.
I am the proud owner of two yorkies. A couple things that you need to know before a yorkie comes to live with you...Yorkies are more difficult to housebreak. (This problem is often what causes them to end up in rescue.) It takes a diligent owner and crate training for many months before they "get it." Don't give up--they will get it eventually, but it is not easy, like some other breeds.
Also, yorkies don't realize their small size. They have big egos. They might pick a fight with a dog 10 times their size. So, proper training and keeping them on a leash when in public is important.
Socialization is crucial for these little dogs. My dogs haven't spent much time around children--so kids make them nervous, and crabby.
Yorkies are loving, loyal, and fun dogs. Food is economical because they eat so little--which has the side benefit of very little poo in the backyard. Yorkies get very attached to their person, and need lots of interaction. Both my yorkies are boys, but I know several females, and they are equally sweet.