Unless you have head problems thats way too much for just a water pump and head gasket.
Water pumps are a 4-5 hour job and head gaskets maybe as much as 10-12 hours and the two jobs overlap. We currently use MB rebuilt water pumps and they are $99.
If you figure 20 hours at 100 an hour that is a lot for parts.
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician