Q: I'm looking at buying one for 16k and the price seems reasonable, I'm triyng to gadge th eprice an dthe possible mechanical fixes that I might hav eto do to it like, brakes, stearing, gear box, possible engine issues since I know very little about diesel engines....
A: I'm very dubious that modern era Mercedes cars have anywhere near the 300-400K mile reliability of their older cars. My '99 E320 is good...for $3000 a year in repairs. This year, the differential had to be resealed, along with a new set of tie rods (second time for this). Has about the same mileage as the car you are considering. My '87 190D, with more than a quarter million miles, is a far more reliable car than the '99 will ever be. BTW, there generally is no such thing as a "tune up" for a Diesel, other than replacing filters regularly.