I would say go with the seller to the dealer, and have him get you the records.
I agree that if he refuses to tell you about the car, or let you get access to the history, then look elsewhere. There are plenty of nice clean benze's out there.
'92 300CE - Sold
2004 C240 - C7 Wheels
2015 ML350 - P1, Pano, Ash poplar wood, Sport Dinamica interior, Running Boards Keyless go.