I'd recommend passing, I have a 2002 c-class that I purchased new and I like very much. But it isn't unusual for owners to have a car with a myriad of issues. It's the cost of repairs, parts and labor, that worry me.
2001 was the first year in the U.S. for the c- class and I've heard people say it's not till 2005 ( or was it 2003? ) that the cars were dialed in.