The Bronica lenses are great. The 80, shot open, does something lovely (not talking to the scientific lens-test crowd, here) and almost magical.
There are a lot of junk cameras out there now from old wedding shops, etc. I've bought 6 or 8 used SQs over the last 12 or 15 years, keeping my main cameras for tripod work and carrying the others when I'm hiking or whatever. Often the film mags are loose or worn down from years on the motor drive. One way to limit your exposure is to stick to SQ-Ais, which weren't made very long, and make sure you get a really tight camera.