I'm a bit confused. So this was an 0.85 MP. Then an M3 top, I assume repainted black, was then applied. But still has the MP finder, right? Almost an MP3, but without the M2 film counter and a few other details.
New black MP now seems to be around $2300 give or take, perhaps a bit more for 0.85. New, non-retail MP3 around $3400 I'd guess. I'd say yours would be nearer the MP value, but all bets are off with the S/N issue. Remember, you've only got to sell it to one person, not everybody. Ebay is great in that way in that you've only got to find the one guy that's interested, if you set the buy it now price well. Just my thoughts.