While I'm not up to date on what the cameras you mention should sell for, I can throw in some background in support of the Sinar F2. While all of the cameras you mentioned are monorails, the Sinar "F" line was designated as their "Field" monorail line (hence the "F"). While not as easy to pack as a true folding field camera, the Sinar Fs were lighter, and designed to close up more compactly than anything else in their line. I had an early model Sinar F, and backpacked with it quite a lot, although I ultimately replaced it with something lighter and even more packable. Also, the entire Sinar line is modular, so that you can swap parts from more expensive models, both in terms of function and format. You can create what was marketed as a Sinar "C" by replacing the rear standard on an F with the yaw-free back from the more expensive models, or (with the appropriate bellows) turn a 4x5 F into a 5x7 F, and so on. Lots of bits and pieces of the Sinar system can be found used. Lastly, in defense of monorails in general, and the Sinar in particular, it will have more and greater displacements than any field camera (i.e. full movements on both standards, and larger allowable amounts of those movements), as well as the ability to extend the monorail for longer lenses, and the availability of bag bellows for really short lenses. While I ultimately traded both my Sinar F and a Wista/Zone VI for my current Canham 4x5, there are times when I miss that old Sinar.