JD 112H round fender

Hey guys, I ran accross a 1967 112H today with a plow and a rear tiller. The unit unfortunately is sitting outside and has been for a year. surprisingly its still pretty nice. It does run and may be for sale. I have no idea what to offer the owner as I don't want to over pay nor do I want to insult them...They use it once per year to till their garden and just bought a new tractor...it is just sitting there looking awesome with those side mount lights...any advice is appreciated!