I have found in my limited experience that if you buy most hatchery stock, you may end up with what you want, but I never have had the quality of bird that I get when I purchase from a very reputable breeder.
I used to go to small animal swap meets. (haven't been to one in at least 4 years) Mainly I went to sell my extra hatchlings. ONE TIME there was a guy selling a couple trios of bantams. They were outstanding. I spotted them from WAY across the parking lot. I told my hubby to go get a trio for me. He came back and said the one trio was a special order that he brought up to meet the buyer. The other trio was still for sale so we bought them. We showed them later that year, beating everything, including the "first choice" trio that he sold.
My "breeder" birds not only are better in conformation but have been healthier from the start with fewer (or no) flaws such as bent toes and other weird birth defects.
Another problem I have run into is people are not very fond of someone telling them their birds are not what they say they are. Often it is ignorance, and they are selling them as such because that is what they were told they were. They immediately jump to the defensive, even when approached diplomatically. They steadfastly hold their ground rather than listen and learn.
Okay, I'm off my soapbox. I think I'll go gather some eggs.