It's not rare but it's extremely desirable (and pricey) because of the lens. If you're shooting primarily B&W, the older Bessa models with the uncoated Skopar lens are worth considering if not for the lower prices. The coated Skopar lenses are excellent with colour film due to their higher contrast, though both versions are corrected for colour. At smaller apertures, it will be hard to see much of a diff between a Lanthar and a Skopar. The Lanthars and Heliars have a very unique look to their pics at the wider apertures.
FWIW, I had (still have) a nice all black Bessa with a Skopar lens until it was damaged beyond repair by some arse*hole. There are all sorts of idiots out there who think they know better.
Yes he did mention that he had special viewer and mask to increase the number of shots ... I'll get him to take some test shots one of these days to see how the lens are doing...
