||The writeup says, "we see no rust, and nice patina surfaces" and that statement has me wondering what the seller considers a rusty bottom. I have to believe there is tons of trouble lurking underneath.
The condition would indicate it had been sitting long term on the ground. My guess is under a dirt floor carport. And that means more problems elsewhere in areas of electrical and wiring, and/or anything organic that might be susceptible to mold, mice, etc.
My limit would be $12000 and even then, I'd be worried.