Try contacting the secretary of the Midland Yorkshire Terrier Club: Mrs K Slaney 01283 226189 and see if they have a puppy register, or whether she can recommend any of their members who breed.
Problem is many people breed what they call 'Yorkshire Terriers' but they actually bear little resemblance to what correct Yorkies should look like. They charge the earth and people end up with something that looks like it was crossed with the local mongrel. The correct size for a Yorkie is up to a maximum of 7lbs (3.1 kgs), and there is no such thing as a 'Miniature' Yorkie - they should all be small, and not the size of a Jack Russell.
Thanks. I do know about Yorkies - my little one of 10 years sadly died this week. I think it is a disgrace where some unscrupulous breeders try to pass Australian Terriers off as Yorkies and charge the earth for them.
Bit suprised at your reply - Australian Terriers cost a lot more than Yorkshire Terriers! (thats if you can find one). I think what you are thinking of are the bigger versions of the Yorkies, which is what I was referring to, often crossed with other breeds and passed off as Yorkies, and then bred on from and so it goes on.