Founders
The five hundred.
Numbered in the order payment confirmed. A serial never changes hands and never gets reissued. When the last one goes, that is the end of it — there will never be a 501st, because the only people who deserve to be certain of that are the ones who bought in first.
#1 is still open1 SOL
The wall
#1 is still open. The first serial goes to whoever confirms first, and it stays theirs.