Hello Daniel,
I too can't quite afford a Monochrom!
However there is a way to get similar without too much fuss!
Shoot raw, use something such as RawDigger to extract one of the four channels. What you get is monochrome data, weighted according to which channel you extract ... R, G1, B or G2. I just tried it on this .RW2 file (embedded JPEG shown):
I used the G2 export from RawDigger and edited it in FastStone Viewer real quick:
This being a rather conventional Forum, I'm not claiming this is the "best way" to get B&W.
Four files
here if anyone wants to play ...