Rare Precancels Value Reference

Can anyone direct me to any list of any reference of any AA precancels values?

... aside from the generic listing of A as $400+, [so, ...more than that...].

I know part of the point is, "well, ... they're rare...",

but I have had a difficult time finding any AA to generically cross reference.

Thanks

IMHO the most important factor in pricing is what state they are from. Specifically, how deep are the pockets of the specialists of that state. Dave Smith's auctions occasionally have one. As I recall, selling prices from 500 to 1000. AA signifies only one is known to exist so it is important to know if the stamp is a second one, or THE only one. In my state (Alabama) we know what the only one looks like and can be considered unavailable. New AA finds happen but you can expect a intensive 'vetting'. There were 7 newly reported AA's in the latest T&T catalog (8th ed). Nominally valued at 1000 each.