i just got a 97 E420 and she also has some rust problems. but i got her for a REALLy good price.

if that car spent its life in OH, that's to be expected I guess. But it'd leave a bad taste in my mouth if the seller didn't tell you about the rust. If he lied about the rust problem, what else isn't he telling you??

I'd get the car up in the air and check for rust on the frame & suspension etc. Be careful and goodluck!