https://web.archive.org/web/20190719150143/https://www.ampr....
They never got close to using the whole /8 and currently allocated about a third of it.
They are using the money for grants and scholarships and perhaps an endowment to fund them perpetually (and just being cynical, probably paying the board who made this decision some of that money as well)
IPs and blocks have been allocated for decades to people for amateur radio related things and will continue to do so without any changes.
But that's outside the scope of what most in the amateur radio community would expect from caretakers of AMPRnet.
Yep, the last /10 went to AWS.
Using this to base the IP address cost: https://auctions.ipv4.global/prior-sales
73 DE WP3NIS