There was a 4a, which I believe is the next larger size, that sold on ebay not too long ago for about $160. The jaws on yours don't appear to line up correctly. That may be an easy fix or a fatal flaw.
It looks to be in decent shape otherwise. If you're selling on ebay then list for a week starting at 99 cents and you'll get a fair price. For a local sale I'd start at $300 and let someone talk you down to whatever you feel comfortable with.
If yours is the 3" jaw version then I'd love to have it, however, I'm a bottom feeder and would never pay what you might get from someone else.