First HAPPY HOLIDAYS to everyone!
I would just like to chime in with my input
, I would always be just a little leery when buying at a swap meet ( for health reasons as well). If it matters to you and you want to start with quality pure bred birds I would start with buying from a reputable breeder. With the new imports and project Orps unforeseen genetic issues are bound to crop up from time to time but with a reputable breeder they are more likely to work with you.
A majority of the time when you cross 2 different breeds/varieties the first generation will look like one or the other and will be sold as such. But future generations will be a disaster. Improper record keeping can ruin an entire flock, even with projects it takes at least 4 generations to get back to pure (sometimes 7 or more generations).
The only other input I would like to add is when someone says "mine are Greenfire birds" or "Marc Sacre's original imported line". Unless you purchase from a specific breeder you can never be absolutely sure where the birds came from. I see it all the time. When I question a bird being sold as one of mine and I am sure it is not, this is the answer I get most of the time
"I bought them from George in AL who got them from Sam's cousin in FL who said they got them form a gal up north who purchased them directly from you several years ago".
It may sound a little sarcastic but it happens all the time. Just let people know where the birds actually came from so they can make an informed decision on their purchase. Once crossed into your own flock they become your own line. So take name dropping with a grain of salt. At the very least ask to see lots of pictures of the parents (not just the rooster or in some cases you'll see just the hen if one is better than the other). Also ask how long they've been breeding the specific birds you are interested in. And most important, do the research and know what they are supposed to look like.
An example I have seen is taking a beautiful show quality Buff Orpington rooster and crossing it into a flock of yellow legged "buff orp" hens and expecting to produce show quality chicks. It's just not going to happen.
Again, if you are purchasing chickens for egg layers or yard candy then all these points may not matter, but if you are thinking about breeding quality chicks you would need to start with quality birds.
I hope at least some of this helps and by all means have fun!