I'd have trouble deciding. On the one hand, I've been wanting a PC Engine Duo for quite some time. On the other hand, the Vectrex looks cool too. Gamewise, there's Magical Chase. Or, instead of blowing it all on one game, I could get several like Ninja Gaiden (the PCE version), Batman (PCE), Earthbound (SNES), Conker's Bad Fur Day (N64)....
In short, I have no idea.