Not too sure, but I was lucky enough to pick up a Site 4 cab (needs new artwork) for $300 recently. The guy wanted to get rid of it apparently.
The game is fun, but with 2 players the end boss is a real pain.
Lately the PCB's alone are going for that. I believe pcnerd on here has one for sale with the guns / marquee for a very fair deal compared to ebay prices.
Yeah your price is pretty steep, $300-400 is the going price for a really nice one. I bought one a few weeks ago in a 33" Dynamo showcase cabinet fully working and in nice shape for $225.