I think it's important to find the breeder first. Find someone that you think does the best possible job in breeding. Learn about their program and what they are trying to accomplish by breeding. Only support those breeders who meet your standards. When you give money to a breeder, you are giving your stamp of approval on their breeding practices. If more people did this we would get rid of all the puppy mill and back yard breeders. I always recommend people check out the Yorkshire Terrier Club of America (YTCA) for ethical breeders.
There seems to be a reverse snobbery going around that if you purchase your dog from a show breeder you want some "la de da" dog, but that's not necessarily true, you want a dog that has been bred using sound breeding practices, and they are much more likely to produce healthy offspring. I get so tired of reading about someone not wanting a "fancy show dog, they just want a dog to love." Well, I don't care if the dog's "fancy, but I do care if it’s healthy, and I do care how it parents are treated. You will also be pleasantly surprised at the cost of show breeders puppy, while they are not cheap, since these breeders aren't in it to make a profit, and the fact that it's important to them to find good homes, they are often much less than you can buy them from a pet store. Many show breeders also have older pups 8-10 months of age who they thought might be suitable for showing and breeding, but who have one tiny flaw, such as being to small, or slightly off color, and are willing to sell these pups very reasonably. Your best bet is to find the breeder and build a relationship. I'm sure any good breeder, will be very attracted to the fact that you work with dogs, and train them. After you find a breeder you like, you have to "sell yourself" to the breeder. See the YTCA website for referrals.
Yorkshire Terrier Club of America About The Club I notice there were 8 breeders on their list fir NC.