Auction Certificates
You can buy a certificate for your auction now, that is a collectable document that will immortalize the auction history and other historically valuable data, along with a secret message you can set (that becomes public when certificate is given to the buyer). You can set an auction to issue a certificate also after the auction started, but not after it ends. Certificates cost 1 credit, non-refundable, and get their own item image and item, that will hold all that data for the sold item.

A first certificate was given to the winner of the ID1 primordial auction, retroactively, because this feauture was inspired by that insane auction (380gold). I will use that gold for rewards, to buy my obsessions and to take dangerous items off the market :D, so it goes back to you.