I'm certain to make some enemies with this statement, but I have to do it, because you're all part of my big BYC family:
PLEASE be aware that even if birds look healthy when you buy them at swaps they can be survivors of dormant diseases. If you ask around you'll find that many folks in this region have bought birds who came in healthy, even stayed healthy through 30 days of quarantine, and yet were carriers of dormant diseases. Infectious Coryza is particularly bad around here, and birds don't necessarily ever show signs of it once they've had it, but can transmit it to your flock and cause you to lose everything and have an unsellable flock thereafter.
It's a necessary consideration when going to swaps, because you can pick it up on your shoes! Think before buying- can you get the desired bird from a breeder as an egg, can you get that bird from a certified breeder, can you get day-olds, etc. Don't risk your beloved birds at home because of spontaneous purchases.
If I hadn't seen more than one person lose their whole business and hundreds of birds to the diseases around here, I wouldn't be so fervent, but I have to be, because I know Coryza and MG are really bad around here. Please be careful.
(steps off of soapbox)