I have one and really like it, but doubt I'd pay $400 for one as I've usually seen them going for less locally (even on ebay).
If you search here you'll find they have some quirks. They don't use discrete output transistors but rather a pack that has no replacement. They have a resistor (in power supply I seem to recall) that runs hot and a mod seems to be favored. If DC offset is ok, then you are ok, but if it is off, it cannot be adjusted but must be corrected by replacing transistors on the output boards. Any work done on the output boards (elsewhere too) must be done very carefully because if you do something wrong you can fry the outputs.
I think the output issue keeps the prices on these lower than other monster receivers. I really don't have an idea as to the failure rate of the outputs, but they do fail and $400 is a lot to pay for something that can become a boat anchor overnight.
Edit: I don't know the Houston market, but if that was local to me and I wanted it, that would be one where I'd play the wait and see approach -- letting it sit on the market for a while so the seller will be more inclined to drop the price.