The Mercedes 300E has frequently been labeled as the best Benz ever built.
But you're looking at a 18year old car, which is not bad in itself, but could be the subject of a few surprises.
The major things that can go wrong are: head gasket, A/C evaporator, fuel distributor, valves guides.
Is the car burning oil?
How's the transmission shifting?
I would have te car inspected before buying it, but for $2,200. you are not taking a very big risk