I searched for Maryland fees for Necropsy. The fee list I found was dated 2006, so it may be out of date, but it said avian pets cost $200 with carcass disposal fees additional, a small charge per pound. With poultry, that would be negligible. Farm poultry was No Charge for the necropsy.
In Arkansas, the cost was $45 for the poultry necropsy with a $15 carcass disposal fee. I'd heard it was only $10 but that's not what I found when I looked it up. This fee list was dated 2008, so maybe it has been reduced, but I don't think so.
The cost can vary widely from state to state and it can depend on how the bird is classified. You might discuss with them how they are classifying your chickens.
ChicKat, when you build your fact page, you might comment on both the widely varying costs for necropsy per state and to be careful how your bird is classified. Just a thought.
The necropsy is free in Maryland but further testing costs $100.