Not a whole lot, £50-100 (or less?) at a guess, though I’ve never followed any on ebay, so a complete guess-timate. No retro value to them as far as I’m aware, as they were Marin “cheap and cheerful” starter full-suss & being brutal the spec shows it. That’s not to say they’re bad, as they based on the Marin Mount Vision frame which I thought was very good (till the BB fell off), and could be built into quite a lightweight decent(ish) bike.
You’d really want to dump the nasty coil shock, put on a modern(ish) air unit with pro-pedal to get the best from it and it’d go quite well ..ok some nice forks would be good too. It’s one of the better versions with the square swinging arm (with disc mount) and not the extremely flexible looking tubular one.