www.ytca.org this is a listing of all the Yorkshire Terrier Club of America's breeders. they are usually the best bet in getting a standard yorkie with excellent health guarantees and a wonderful breeder to be there for you no matter what as you learn about yorkies and raising and loving them.
or go rescue route and
www.petfinder.com has lots of listings by area and prob has lots of yorkies of all ages for a really decent adoption fee that usually includes their shots and spay/neuter and saves money in the long run of you having to do it all yourself.
either way you'll get a sweet baby. just watch out for back yard breeders BYB or greeders we call them on here. they only do it for the money and they are not breeding quality dogs with good health. they won't care about you years down the road if you need them and don't back up their dogs when something happens genetically in their health or life.
make sure you always go see the breeder's home and the pups mom and dad and ask about all the health checks done on parents and guarantees on pups.
GOOD LUCK AND WELCOME TO YT!!