Don't due it unless you are willing to budget and shell out an average of $2000-$2500 a year in maintenance and repairs (equivalent to a $200 car note which you are trying to avoid) My Benz - E350 was a tank, and got me to 250,000 miles before I got ride of it - but the stuff that went wrong - a lot of electrical issues with windows, door locks, speedometer panel LCD needing replaced. I was replacing a tail light about every 2 months, and got pulled over twice for that.
If you do get it, ask around and find a good independent mechanic who primarily works on Benz's or at least specializes in German cars. The equipment, scanners, etc used can be different which some generic shops may not have, and you will be visiting them a lot (just my experience, but others may have had better experiences with the Benz's)