Realistically they're not worth all that much, fun game to play but there are quite a lot of them around, so not exactly rare.

I think maybe $1200 for a very average working machine, maybe needing cab respray, BG sealing and touchups and maybe a bit of playfield work.
Perhaps $2K - $2.5K for something thats really good with no work to do.
This is based on what I have seen this title sell for in recent times and the fact that its a buyers market at the moment.

The one on Ebay is way overpriced IMO. The cabinet is very very rough and in need of  a lot or work. The BG and playfield seem pretty good and the displays look clean and bright with no burns, all in all it seems good but maybe $1500-$2K overpriced.