Although she can be pricey and some others on YT may disagree with her misuse of the word "teacup" I have purchased two yorkies from her (which you may view in my album) They are just over one year old and amazing! Here is her website:
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She is not in Boerne, but unless she moved to Helotes already I think she is still in NW San Antonio. Her name is Karen Ortman. Good luck finding a yorkie.