Hi and welcome to YT and how nice of you wanting to find a yorkie for your friend. Being that you want an older yorkie, I would suggest checking with rescue organizations. I currently have 2 rescue yorkies and both are going to make a wonderful pets for some lucky family. You would be surprised at the number of yorkies surrendered to rescues. I'm sure there are several organizations in your area that could help.
Good luck on finding the yorkie you are looking for. You'll have to post pics when you get one.