Using Forth instead of BASIC and being all white in a era of black and beige 8-bit machines, the Jupiter Ace never really stood a chance. Not that it wasn't an interesting and cleverly designed micro, mind you, but those markets have always been too fickle. Anyway. For a chance to own one of these rare computers at a sensible price I suggest you have a look at this actually affordable Jupiter Ace eBay auction.
The micro is sadly scratched and looks pretty scruffy, but seems to be operating properly. It also comes with mains adapter, TV lead, cassette player cables, demo tape, manual and 6 tapes worth of games.
Seller ships to most of Europe, Australia, Russia, USA, Canada, Israel, New Zealand and Japan.