Definitely get it checked by a Mercedes specialist. Spend the extra cash for a professional non-bias opinion. Then use that to bargain with the seller (maybe you could get him to lower the cost of the car by 1/2 what it would cost you to get the minor things fixed).
I bought my Mercedes with a "few" problems that I felt were fairly easy to fix, but after having the car only a year, I've already put in an additional $3000 into the car.
Don't get me wrong I love my car, but there are a lot of "small" things not working that irritate the **** out of me. I'm also too stuborn to over pay for a minor problem (ie, $200 to fix the odometer).