It's not quite this simple, but it's almost this simple - if you are a DIYer, and you enjoy working on your own cars, owning a used Mercedes is a great thing - you get to work on it, you buy parts mail order for reasonable prices, and you get solid, safe reliable transportation at a reasonable cost. But if on the other hand, you are not a DIYer and you simple take your car into the shop and say "fix it", owning an out-of-warrenty Mercedes can be an anguished nightmare. I'm convinced there are not too many exceptions to this rule.

But this sounds like a nice car, you like the body style, you've got an honest mechanic, and it sounds like he'll work with you on it. I wouldn't rule it out. It really helps if you just want to get involved in maintaining it. You can make up for a lack of skill with a certain amount of enthusiam. There's actually a lot of information sources out there, including the archives herein, to make it easier.