work.
How many miles does the car have?
It’s possible the crankcase ventilation valve should have been done long ago. You really don’t want to mess with not doing the maintenance work required on those.
Again the transmission filter is on a miles based schedule and should be done as required.
The transmission pan gasket is a by product of changing the filter.
As already advised, it may make sense to sell and avoid the cost of that maintenance work.
If you sell will you tell the buyer of the recommended maintenance work?
That work is not difficult to complete, but the quoted price is to be expected for high end German cars.