The cost to replace an intake manifold gasket will depend on the make and model of the car and how hard it is to get at and remove the intake manifold and replace the intake manifold gasket.
Most shops though charge between $200.00 to $450.00 to replace the intake manifold gasket on a vehicle.
The intake manifold gasket itself is pretty cheap but the labor charges is what cost the most because on some vehicles you have to remove a lot of things to get to the intake manifold and remove and replace the intake manifold gasket.