So maybe add an imgur link showing cards and extras if we don't want all that uploaded to the site? From what I understand, imgur links don't expire unless a delete is requested, but it would suck if imgur went down or something.
Some of the NTSC-J games I've collected over the years have come with 4 or 5 cards, and each one typically has the PS2 catalog number written on it somewhere (SLPS, SLPM, etc). It could be interesting to see them, so you know what to look for in auctions and stuff, but otherwise I guess I could just say "comes with _ extra cards" or something.