I'd say you can figure 80% on a very good condition marker like it could be put in the box, sealed and damn near pass as new. 75% value on a pretty good condition or minor wear here and there. 70% on a gun that shows obvious wear from heavy use but no serious blemishes. Anything in worse shape than that is a case by case basis and generally up for offers.
I would say anywhere from 7-800, depending on the condition and what's included. I'm not sure how many were made, but they seem rare enough to hold most of their price well.
