Hello Snoopy, IMHO- I prefer the older cars (116,123 diesel MB; Series III Jags etc.) but for your sister I would recommend what others have already stated- "the smile factor". All cars drive differently and I believe that I just have to "feel" the right one. I find the 124's handle more like American cars than European.. perhaps your sister would prefer that. I am always looking for/at older cars and am now searching for a friend of mine who wants one just like mine. I find the back roads offer used auto dealers who are willing to deal more with a buyer than big city folks. I wold take the following steps in choosing a vehicle for your sister: Have her drive and pick out 2 that she "smiles" about. Then find someone who knows something about MBs and let them drive those two and give their opinions. (what sounds do you hear traveling 5-15mph? How is the accelration/gear change? Does it shimmy at 60 and level off at 62? How does it feel at 80mph? etc). When she picks the one she wants, see if you are allowed to take it to an MB mechanic to inspect (might cost a little, but he can give you knowledg about the engine etc. that might save you headaches in the future). If someone knows about MBs they can tell you what might need to be fixed/replaced in the near or far future. Having said all that, I too believe the prices are way to high. Even with the relative low milage on the diesels, for $7k you would be hard pressed to get your money out of it through resale. I just paid $2k for an 82D that NADA lists for $4900 in perfect condition.. mine is 98.7% perfect... so the deals are out there, one just has to spend the time to look. Good Luck!
1982 300D (266,001 mi.) looking and running great
1976 450 SLC
1982 Jaguar XJ6 (loved, but gone)