[Arran]

It sounds to me like the volume control was replaced by a random potentiometer that someone had laying around in their junk box, a linear pot for a tone control for example, I wonder what kind of hack job was done on the rest of it? The broken dial scale is a definite detractor on the value, those rarely get damaged unless someone was being rough with the chassis. It sounds like an as is radio, no I would not pay anywhere near $150+ for it even if it does sort of work, if you can't get more then what you paid for your old sets neither will he, he isn't being shrewd he's being delusional. I would offer him $60 for it, if he's serious he will counter offer or take it, if he just laughs it off or gets steamed walk away.
Regards
Arran