The rare and wonderful successor to the PC Engine, the 16-bit powerhouse that is the NEC PC Engine SuperGrafx may have failed to dominate console gaming, but it did get a select few excellent games released for it while retaining full backward compatibility with the PC Engine and even its CD add-on. Oh, and the SuperGrafx was exclusively released in Japan.
To own one, you could try your luck and bid on this PC Engine SuperGrafx eBay auction. The console comes in its original box with power supply and controller and five obviously rare games: 1941: Counter Attack, Aldynes, Battle Ace, Daimakaimura (Ghouls 'n Ghosts) and Madō King Granzort.
Seller ships only within the UK, but one can never know what asking really nicely can accomplish.