Thanks for the reply. Does it help the resale value to replace parts like the rusted split-top hinges, pitted plastic leveling feet (maybe the legs) and diamond ramps vs. keeping the original patina? I'll clean it up, but I'm not sure if the condition evaluation has anything to do with original parts vs. replacement parts. Thanks.
Resale is helped by making the table play well and look good. No added value for "patina". In fact, the particular patina on this table hurts its value. That said, if you go ahead and replace a bunch of parts, as AT said, you will probably not recoup the cost. Replace parts that affect play. Rusty hinges, etc. can be cleaned up.
I personally would be concerned about the water/beer damage. The particle board in these tables swells like crazy when it gets wet and it stays that way even after it dries. I'd check to make sure that the water damage has not affected the playfield or sidewalls.
Brown marble tables in my neck of the woods can easily be found for $300-400. There is one on Craigslist now (Asheville, NC) for $150. That one is in fairly rough shape, but not too different from the one you are looking at. IF the one you are looking at is not water damaged (which would be a deal killer) I'd offer $200. The seller will probably not take it, but as Alaskan Thunder mentioned, you would have to put some money into that table to bring it up to snuff.
If you can be patient, better tables always turn up.