I had a CL score [impulse buy] this weekend. I picked up a tank, fender, and seat for $100. The tank was primered and seemed to be repaired based on the magnet test. When I got it home and sanded it, it became more ugly-duckling and less beautiful-swan. It doesn't have any major dents, but it does have a few minor ones that need to be addressed. I will probably make it work. It would be a good candidate for the rusted look.
late 70s Yamaha DT250 or DT400.
This is the shape I am after. Flat for the first 80%, then an upsweep for the last 20%. I guess I could make a new seat pan with the shape I want, then steal the cover and foam from this one. That's a pretty dirt-bag option, but it would be cheap and easy.