I recently purchased a 400E, I looked extensively at approx. 12 cars, mostly 300E's (92's up)and 4 400E's. Take your time, don't jump at the first one you see. If your not capable, have it looked at by a trusted mechanic, and a body man if possible. On the 12th car I found one that had absolutley no body damage whatsoever. (a Very big consideration in my mind, especially if no written documentation on history of work).
I have a checklist that I used in checking out each car, that becomes a great help. If nothing other than keeping them straight in my head. Drop me a line and I will send it if you wish.
A couple of things to keep in mind when looking:
1. You're the buyer, you are in control, don't lose it.
2. While the color might not be what you like (Signal Red, in my case,) don't let it keep it from the purchase, resale after your done with it will also be important. If you don't like it, someone else might not either.
These cars very predictable, i.e. what happens to one usually happens to others.
Take plenty of notes, ask plenty of questions, take your time.