knock on wood i have not had any major trouble, maybe 300$ at most (not including normal maintanance which either saves or kills these cars!!) with my 94 280 (93,000 Mi.). but i have noticed mercedes are either unbreakable or always in the shop.
But for the bills it is hard to justify them some times, i had a 190E that had lots of troubles <1800$(motor mounts, timing belt(almost snaped), new fuel injectors, radiator, O2, at one point it was blowing out fuses like crazy?). But a point came when i only fixed what was needed and either tryed to fix other thing myself to save$ or lived with out it. But once you get a good one you develop a loyalty. mine is to german cars in general.
Look at the pole question would you buy another 202 it might help