I think a very nice one would probably bring close to 2K... So, use that as a starting point. I've been casually looking for this title for a few years and followed your thread. It's cool that you got the drop working but, in order to get top dollar for this game, you will need to find the player who loves the game (not this player) and will probably have to ship it. I'd be willing to suggest that someone with a decent DMD game would probably trade you for it but obviously, you have to be super patient with a trade. A 2-3K trade could be possible to the right person that is tired of their DMD game.
On a somewhat related note, Dirty Harry sample machines with the drop do command a premium, over a standard nice DH. There is however, a more specific market for HMM so it could take a lot more time to find the right buyer.