I'd start low (<$500) and go from there. I wouldn't pay more than $750 for it. It's probably heavy and you can count on replacing all the rigging.

You'll want to replace the tires on the trailer at a minimum. Maybe bearings and lights, too.

Examples - paid $650 for an early 70's Turbo w/ painted trailer. Hulls, frame and mast are in good shape, but took a lot of work to clean up. Tramp was OK, but no straps. Ended up being a little heavy (257#).

Paid $1000 for an '85 sub-minimum weight (240#) standard 14 w/galvanized trailer. Tramp was usable, but no straps. Hulls, frame and mast in excellent shape. Only needs to be buffed out.