I think you should buy the breeder first before even looking at the puppies. I went with someone well known on here (Deb Sillers and Amazing Yorkies) because:
1. She has been around here since about 2005 or so, so I knew she wasn't part of some fly by night operation.
2. She gets so many good endorsements from members here who have her pups and outside of this site all the info I found on her was very good too.
3. She gives a great health guarantee: 1 year on joints, 5 years on almost everything else (e.g., heart, liver, kidneys, etc)
4. You can tell she loves her pups by the way she writes about them (e.g., her
"crappy" day with Vinny) and she answered tons and tons of questions I had when I talked with her for a couple of weeks about her pups, her operation (Amazing Yorkies), and how I need to take care of a pup I might get from her. On a side note, Deb was really great in helping me those first couple of weeks too after I got little Cookie and had tons of questions (only other pup I had raised was a mastiff, and it's worlds different).
5. I talked with at least 30 other breeders and liked Deb best.
And as a huge plus, her yorkies really are beautiful, and then the girl I got from her was so well socialized that Cookie and I were friends and playing by about 20 minutes from the time I got her home. Long story short, pick a high quality breeder first and getting a healthy and fun pup will take care of itself from there.