I paid $600USD for mine in great shape, clean, complete, with box in very good condition, wheel, sleeve for wheel, 3D Minestorm & manual (perfect/un-creased/un-written in), imager instructions, and printed promotional materials/offers. Yes, they can go for much more as Tony says, buy loose - expect $400-$450USD from the past handful of loose-Imager Ebay auctions I've seen.
I will say say one thing. The Madtronix Imager works better than the original. Saturation is better, shapes are for more consistent as a different color, not to mention its far cheaper. With the reproduction you do not have to worry about the foam forehead insert deteriorating and it has the provision for any future game specific color wheels.