How about a 1995 AWD Subaru Legacy Wagon vs. a 1992 MB 300TE 4Matic Wagon? I have both, though the Subie has only 118,000 vs. 139,000 miles on the W124. So which is more maintenance free? Three guesses and the first two don't count. But which would I rather load the family into for a long trip? or drive home in a blinding snow storm? or on the highway with trucks? the W124 hands down!
While the MB is more labor intensive, and I have a love/hate relationship with it: love it when it works, hate it when it breaks, it is all well worth it. And contrary to someone's post, I have found the repair CD quite good and very helpful, not only in finding the correct part numbers, but also the schematics for doing the job. If you are moderately adept at auto repair, and willing to try new repairs that appear challenging, you will save lots of $$. This forum is also an idespensible source for information as you know.
We got our W124 used and have since paid a professional to replace the timing belt and transfer case. In a non-4matic you won't have to do the latter. I have replaced the water pump, the serpentine belt tensioner, all brakes and rotors, all radiator hoses, the radio, (rebuilt by Becker), rebuilt the power antenna myself, and added Hella Euro lights, not to mention the routine preventative maintenance. Have we put money into the car? without a doubt. But the way we look at it, for about $20k including the initial cost of the car, we have a spacious seven seat vehicle which is better built and styled than any comparably valued vehicle, and certainly much less than a new MB or other make would be. Plus, the insurance and yearly taxes are much lower than that of a late model car, and even a new car is not without repair costs.
I think you are smart to look for this model vehicle. You can't go wrong with a used W124, but be sure it comes with a complete service history. If you don't get a used W124, get a Subaru - it'll cost you only for gas and an occassional oil change - but you could do that yourself. Enjoy. And remember, the hunt is half the fun.

1962 MB 220SEb "Fintail" Sedan
1963 Vespa VNB Motor Scooter
1992 MB 300TE4Matic Wagon
1995 Subaru AWD Legacy Wagon