It's a long shot, but if anyone has a ZM 18mm finder and is looking for a 21mm finder, I would be interested in a swap. I used to own the 21mm biogon, and I sold it, in the meantime acquiring an 18mm. I kept the 21 finder as I was using the 18mm on the M8. Now I have an M9, so the 21mm finder is no longer necessary.
I would rather not sell it, as it is such a good finder and I would rather keep it around in case I wind up with another 21mm lens. But I would love to trade it!