I love my 28K and the sound it makes, but then again, it's a handcrank and not electric.
Before I made an offer at all, I'd look under that scrap that was used as a pincushion and see how much "pin rash" is there...on some machines it's down to the bare metal.
I don't see a lot of rust, mostly just looks dusty to me..and that's an easy fix. If it were me, I'd offer 50 or 60 dollars for it...but you'd also have to consider that I don't like the Godzillla finish..