If you're in the UK, looking for a boxed Super CD, you could do worse than this one : http://www.ebay.co.uk/itm/PC-Engine-Super-CD-ROM-2-Unit-Boxed-/290704170787?pt=UK_VideoGames_VideoGameConsoles_VideoGameConsoles&hash=item43af519f23
Without the international shipping, that's pretty damn good value IMO. Nearly snapped it up myself.
Apparently it was a good deal, since it has ended. :)
Great deal indeed. Its tough to find one both working and complete with box instructions. I wouldn't sell mine even for 5 bones cuz it was so tough to piece a nice one together..