The term "teacup" is a marketing term, and not a recognized designation by the AKC.
This was on another thread and it's a must read for anyone looking for a yorkie pup!
The sad truth about "teacup dogs"
If you find a breeder offering pups for less than 250, most likely they have cut some serious corners in their breeding program and you will be in for a lot of heart ache in the future.
You may, however, find a dog that is in need of a rehome in that fee range.
Do your research, take your time and good luck.
Try looking on petfinder.com . I do know that there are some reputable rescues in Texas. Can't remember the name of the big one right now...