At certain auctions, like Mt Hope they specify with each bird at time of auction if it is from an NPIP flock or not. You can then get the NPIP paperwork from the auction vet. These at times will bring a higher price point b/c of the NPIP value, but not dramatically so. Whenever purchasing from an auction get the health papers if available to you or they will supply them. Often it lists the previous owner info also.