Is $500 fair for a valve cover gasket replacement? on 2000 Nissan Xterra

Oil leak showing on undercarriage. Diagnosed with valve cover gasket problem.

Asked by for the 2000 Nissan Xterra
The estimate is about right for both valve covers. Note oil leaks can be difficult to pinpoint the source at times and sometimes cronic in nature on high mileage engines. As the engine ages and develops more crankcase pressures due to worn piston rings and wear in valve guides it has a tendency to build some pressures that PCV (ventalation system) may not handle thus forceing oil when under loads.