Well, the w124 is a good body style etc etc, but just so you realize, buy the car for $5K and then keep 5K aside for the repairs coming your way in the next 3 years.
You'll get a zillion replies on this post, but the bottom line is the w124 has it's share of problems, more so than any other mercedes model in my opinion.
Bottom line... put money aside for it's repairs (lots of it) and don't just focus on the selling price as it's total cost of ownership.
Whether you think you can or cannot, Either way you're right!. by Henry Ford.