Call me suspicious, but why did the PO decide to get another with half the mileage? Does he know something you don't know? Best case, he was experiencing no trouble, but wanted to get out of it before he did.
This is very high mileage, and I would expect you could find a low mileage example easily.
'84 Euro 240D, 523K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in