A copy of the ASDI block list is on https://www.muckrock.com/foi/united-states-of-america-10/faa...
The FAA also has a new program to hand out pseudonymous aircraft identifiers via commercial providers so there probably is a fee for that https://www.faa.gov/nextgen/equipadsb/privacy/
Feeders sending them free data for fake enterprise dashboards and fake "$89 value" accounts have made David Baker a multi-millionaire.
As for military stuff - they have additional capabilities for their transponders that provide for responding to interrogators (think identify friend or foe - IFF systems). They're not supposed to disable transponders in the required airspace - they've got to comply with the FAA rules too. There are situations where ATC transfers control over to the military where they are free to do more things. Like in a hot military operating area (MOA) or when ATC transfers traffic separation to the military (MARSA).
Do you know more about how this is done? Is there a fixed price list for this service? Can one "buy" it online? Is there some sort of registry that is shared between networks?
> Additionally military aircraft are typically not reported.
While I'm sure the military can turn off transponders at will, I presume (?) they often fly with them on. Can these signals be tracked with "standard" gear when they are on?