Look up the icarsoft i980 or MBii. It makes diagnostics and repair of a w211 a piece of cake. I used to have the same fear the electronics in more modern MBs until I picked up a dirt cheap w203 c320 wagon. After a bit of research and the right CANBUS tool, I brought the transmission out of limp home mode, fixed the power seats, cleared the SRS light, fixed the AC, swapped a 3 spoke steering wheel with functioning buttons. This thing doesn't even have a dipstick but I have 3 different methods of measuring the oil level. When I got a misfire code, I knew immediately that it was cause by cylinder 3, sparkplug B (12 sparkplugs). The plug wire boot had popped put.

If you're at all handy don't let the electronics spook you. Yes the 124 is nice (I still have mine) but a 211 even nicer.

__________________
CENSORED due to not family friendly words