SNES CD system.
You can see in this early prototype the beginning of what would become the PlayStation controller: the triangle-shaped start button and the eight gameplay buttons (two of the face buttons would become shoulder buttons in the final controller). This thing would be the prize of any game collection. We don't know how this eBay seller got his hands on this thing; we'd expect it to be locked up in Nintendo headquarters somewhere. It must have been an ordeal to obtain.
It is priced accordingly.