I'd think that 300SE would be very much worth 1200-1500 if it is roadworthy. The rust would be the most worrisome thing. I have seen some rusty late 126s, but they mainly seem to go around the sunroof and back window, and wheelarches.

And as jfsehl says, that's a lot of car for such a pittance. I bet it could make a good project car. Or maybe I just feel kinda sorry for it.

That beautiful 560SEL ended up at $12100. That's more than 95% of them go for nowadays, but it's sure a nice looking car.