Get the VIN, then run a Carfax report (or something similar though a dealer friendly to you). You could also post the VIN and let us see what it tells. That price sounds too good to be true. I would suspect frame damage and/or odo rollback at that level. Have a competant professional check it out for you. Paint, panels, VIN check, mechanicals, service history, etc. If it is a 92 500E and has not been hit every panel (bumper, fenders, door, trunk, etc) should have a MB sticker with the VIN on it. The numbers should match and be 500E VINs.

Best of luck...let us know how it turns out.

Hope this helps...Lee