If I really wanted one - I'd pay it. I've had a Cube before, so it's not all that interesting to me these days. But a machine that I desired that was new-in-box? Sure.
I'm guessing it seems fair, considering most used examples are fetching $200 or so. Who knows, it just might explode in value eventually, but at the moment I don't think I'll plunk the dough for it ;p.
Yeah, maybe in 15 years if they wanted to save it to sell it later as a collectors item. But as old as it is, buying it for more in a sealed box so you can use it @ +250% the going rate of a used one is dumb.