How much money are we talking? I had one person tell me that brand new chicks were too young to be tested for the sale but I am not sure if that is true either.
The tester buys the antigen. He needs .25 per bird just to make back expences.. It is true that birds can be too young to be tested. If they came from an NPIP flock you are OK. You only test birds old enough to breed from what I have heard.