There's a lot of neat things you could add to a Collector's or Deluxe Edition, stickers, trading cards, keychain, a tiny printed out Bitcoin white paper, challenge coin with HoB Label, lithograph print of the HoB label, a patch with the HoB label, CD of the soundtrack, printout of the game map, and enamel pins. Obviously these little items can get expensive so you have to weigh the costs/benefit of each.