2002 Mercedes Benz C320 Am I being charged fairly for these

My car started to shake while in gear and in idol. Unfortunately I can't afford to take it to multipule places for estimates. Your advise would be very apprieciated.
We took it in and were told the following needed to be done.

*Replace ignition wires
*Replace 2 cover gaskets on top of engine that are leaking oil onto spark plugs.
*Replace cabin filter
*Replace fuel filter
*Clean spark plugs

All parts and labor $800 total.