Parts I,ve had to replace ('96 C280, 150,0000miles):
Fuel pump relay (in the trunk).
Fuel pressure regulator.
Vacuum lines and rubber connectors under plastic cover on top of engine.
Head Gasket.
Water pump.
Compressor.
Fan clutch.
Fuel level sending unit.
Front flex disk.
Lower control arm bushings.
Power steering pump.
Steering damper.
All of the big ticket items were done recently.
...aside from these, everything has been fine.
Only use MB approved coolant(Zerex G05 is one). If it has the green stuff in it, get it out, flush the system and put in the good stuff. You,re radiator will thank you for it.
If you are serious about doing maintenance/repairs yourself, go to the dealer and buy the service cd, ~$100(need computer with Windows Internet Explorer and Adobe Acrobat reader), well worth it.
Good Luck, Dan