Purchasing Warped Roof 1997 Bigfoot 2500 9’6”?

I think it is a good thing that you passed... Even for $3,000 it sounds too far gone from what you described.

I once paid $3K for camper that was less profound, I knew I had to do some work in the OH area and knowing now I would not do it again.

If water is dripping then it is a complete rebuild and IMHO, not worth much.
For you, it is a good thing that he did not take your $3K... from waht you describe, you would be doing him a favor to remove it at no cost.