The smaller four offered on these cars (1.9 or 2.0L wasn't it Johngenx?) was a problem.
In North America, only the 2.3L SOHC M102 four was offered. The 1984 model engines are different, and not very good. Any 190E from 84 is to be avoided for many reasons, but as they're now 21 years old, that is enough of a reason. In 87, the 2.3L was uprated from 113 to 130hp, making the 87's the earliest models to be considered. But, with the age of all 190E's now, I really would only consider a 91 or later, and reluctlantly unless the price was very low.
The only truly desirable 190E is the 87 190E 2.5 turbodiesel. The 2.5L diesel is an incredible engine and in the 190E body, offers great performance and unreal economy. They also just never break. Most of the gas engines (2.3, 2.6 and 2.3-16V) easily go 500K without work, but the little diesel can outreach that by a large margin. There are several in Alberta with over 800K.
Personally, I have found brake parts very reasonable. I do buy OE from the dealer since I had such bad luck with jobber parts. Some people don't like the fact that MB brake discs are not be turned on a lathe, instead replaced. But, they're cheap, so that's fine. Just after I sold the 190E, I helped the new owner with a brake job. Front brake parts were $70 for the pad set including the caliper bolts and sensors and $90 for the discs. I don't think $160 is expensive at all! Ironically, parts for the C230 are actually LESS. I bought front discs for $65 for the pair.
Some parts are really, really, really expensive. Like engines. If you need a new/rebuilt engine, it will generally cost way more than the car is worth. But, their engines are usually the last thing to ever fail on the car, so no worries. In fact, I have yet to find an owner that has changed the oil that has had a bottom end actually wear out. Regardless of mileage.
One nice thing I've found is that many parts are repairable or rebuildable at a fraction of the cost of new. In fact, MB offers their own rebuilding service and it's awesome. My Dad has a 1973 300SEL 4.5 and parts can still be ordered right up from MB, and some stuff that was really pricey, we had rebuilt at about 25% of the cost. This is a boon to owners of older cars.
Overall, on a cost per mile basis, no car we've owned has been more frugal than the C230. It's very DIY friendly, has had few repairs, and is good on gas. I've recently switched back to the OE 15" wheels from 17's and that should save some real bucks on tire costs.
