I suppose whatever the market will bear - there are few of them around, and used ones are now going for more than new ones went via the threads around here.
Best offer might be the right way to go.
I have not yet heard the stock one, but thanks to Vinnie's generosity, I have sampled the modded one. Really nice sounding unit, and I would have bought it, but it did not quite match up with the rest of my system.