I doubt it would sell for less than $500 US. Maybe more.
Having said that, if they integrated a scrub wheel with assignable buttons for all of us video/audio engineers, I would totally buy one. Sure, you can buy dedicated ProTools, Logic, or FCP keyboards--but to have a perfectly customized keyboard interface with every pro app or high-end game you own, changing on-the-fly in every new scenario, well, that is a transformational innovation.
It totally fits the Apple ethic of a brilliantly designed user interface experience.
Apple should take some of that iPod green they've banked and buy these Muscovtes completely out--lock, stock and ruble. Mac OS X Lion should have it implemented on day one for all the Apple pro apps, with an easy-to-build developer's kit to get Adobe, ProTools, and the gamers on board. The new PowerMac G5 with Color-ProKey technology!
The best part of it--adding this functionality to Longhorn would delay its release another two years! And you can imagine how gawd-awful that would work in that environment?!