Have you looked on Petfinders classified ads?
Often there are adoptable yorkies and other small dogs that people can't keep for whatever reason and need new homes for them.
Look at this one I found:
dog: Yorkshire Terrier, Yorkie
7-16-2007
Id: 1423619
Owner: Bay City, TX
xstitch44@yahoo.com
Nancy
Age: Adult
Sex: Female
Size: Small
This little girl is very sweet! She is AKC registered and is spayed. She is being placed only because of the owners health problems. Please email for more info and a picture. There will be an adoption Fee.
Id: 1416374
Owner: Denton, TX
brad.gandy@verizon.net
Jamie Gandy
Name: Magic
Age: Young
Sex: Male
Size: Small
My mom is unalbe to care for dog so he needs a good home. He is excellent with children and can be an indoor or outdoor dog. He is a yorkie mix. There will be an adoption fee to inusre he will go to a good home.
Id: 1413154
Owner: Denton, TX
9405979641
livetoshine@hotmail.com
Ashley Browne
Name: Coco
Age: Young
Sex: Male
Size: Small
1 year old Purebreed Yorkie. Gentle and good with pets and people. Loves children. Inside and outside pet. Has all shots.
dog: Yorkie
7-01-2007
Id: 1412903
Owner: Teague, TX
boxerchimom@yahoo.com
Angie
Name: Cassie
Age: Young
Sex: Female
Size: Small
I have a female yorkie for adoption she is 8 months old. Adoption fee does apply. No scammers please!!! Please put the name Cassie in the subject line or you will not be replied to.
PLEASE don't buy from a pet store. If you do, you are just subjecting the puppy's parents to life in misery.