I have one tip for buying from an auction: DON'T! I would not buy birds nor hatching eggs either. Some diseases are passed along through the egg, some are not. So if those eggs are contaminated it's no better then bringing home a sick adult bird in my opinion. You can read over and over on this forum about people who brought home auction birds, sometimes even quarantined them, and had illness show up. To me it's just not worth it. a bird who is a carrier can look perfectly fine for a very long time, showing no noticeable signs of disease. Illness may or may not show up during quarantine.
I raise my own chicks and never have need to buy adult birds. If I did it would be from a reputable, NPIP certified breeder. You always run a risk in bringing home new, adult birds but there are ways to minimize it. Auction birds with their unknown background are a huge risk.
I guess it also depends on what you've experienced in the past with your flock. Those who have never had the hassle of dealing with a disease outbreak, and the upset of deciding whether to treat sick birds or to cull an entire flock and hope that you can kill off whatever disease remains on your premises... if you've never experienced all of that then a person might be more inclined to say "sure, auction birds are fine.." I think you would be hard pressed to find anyone with experience dealing with an outbreak of any disease to feel inclined to take the risk!
