I purchased a 1994 E320 Cabriolet last year for $21K. It had 65K miles and was near perfect in and out. Remember this was an $80K car when new and did NOT stay in showrooms very long. (alot of$ back then & now too!)
As mentioned the wiring harness is a weak point, and if not replaced yet, will eventually need to be. Not a deal breaker. Also, the front timing cover will leak oil, not a big job to fix. The head gasket will bear examination for leaks.

This is a great motor, good torque and great gas mileage. Straight six is cheaper to do a valve job when needed. The bottom end will last forever.
Check transmission for burn smell. Check maintenance book for stamps. Look to see if 60K mile service done, if not change the trans fluid & every 25-30K miles thereafter.

Just make sure to look for the proper top operation (quite complicated). Make sure the leather is soft, look for paint/body work (check to see is all the factory body panel bar code stickers are there. Do a Carfax to see where car was delivered and licensed since new (rust belt States!) The A-C should be 134A on that car(which is good)
This was one of the last MBZ cars that was somewhat "hand built", other than the 500E/E500.
Good luck