I also used to own a W220, a 2001 S500 to be precise. 2 months ago I purchased a 2011 S550 RWD with 48K miles. It has all the options(parktronic, Distronic, dynamic seats, AMG package) except for the night vision. Paid 32K. Very happy with it. No issues what so ever. 35K is a tad high in my opinion, if it does not have all the options I listed.
I would recommend you take it to a dealer for a pre-purchase inspection before you finalize on it. It's also due for a transmission fluid flush at 40K miles.
I would recommend you take it to a dealer for a pre-purchase inspection before you finalize on it. It's also due for a transmission fluid flush at 40K miles.