welcome!
rust in the frame - especially midway back. look for it in the window sills, gutters and front A pillars.
over the rear wheel wells is common too - make sure to check for bondo or similar hiding cancer.
pricing really is all over the map, but a lot less than it was a couple years ago. Can't be much help there i'm afraid. We pick up 2F 60's anywhere from $500 to $7-8k depending on condition.
you could always post up pics and someone will give you a ballpark $ if you are trying to bring the seller down a bit.
I'm just south of you a ways - i know what you mean by wet (except for today which is gorgeous outside)!
GL!
rob