I live in Utah & know of many reputable breeders throughout the state. Depends on what you are looking for ( AKC, Parti or traditional yorkies and price. ) Let me know about the size, age etc... and I can point you in the right direction. Good luck in your search! Yorkies are a handful of fun!
You will also want to interview each one, ask questions, are you looking for an AKC yorkie to add to a breeding program or for a loving pet? Most breeders will be more than happy to answer your questions.
Also alot of website breeders have go over their background & breeding practices, you can do a search in google for example, AKC yorkies in Utah, or Utah yorkies ...etc.. and find a few there as well.