I don't mean there are 50 of them on any given day, but they pop up pretty regularly. Space Duels have been getting parted out for a long time now, since the monitor is worth darn near as much as the complete game. As a result, there are a lot of parts out there. Heck, I've got one in my garage right now that's been converted to Neo Geo, complete with two sticks. Keep watching, one'll come along.
BTW, you might find more if you spell it Space
Duel, instead of Space
Dual.
