I don't really think of myself as a collector, but I've bought and sold a few old Voigtlanders, so I've watched the prices on those. Earlier versions of the Bessa aren't usually worth as much, because they don't have coupled rangefinders, so a Bessa I with a Vaskar lens might go for under $100.
6x9 cameras with coupled rangefinders generally sell for more money, and the Bessa II just has everything going for it--great coated lenses, coupled rangefinder, compact design, nice finish, well made leather cases, and vintage styling.
If they would just have put the shutter button on the top plate of the camera body with the door hinged on the right side, like on the Perkeo II, instead of putting the release on the door, which is hinged on the left side, it would be perfect. I found it tricky to hold the camera steady in the horizontal position.
Another issue which is common to all folding rollfilm cameras is the problem of film flatness. To fix it would be to make it a much heavier and bulkier camera, though, like the Fuji 6x9 rangefinders, so it would no longer be a pocketable 6x9 camera. A Linhof 6x9 back is heavier and bulkier by itself, without even having a lens, shutter, or bellows.