1994 Other Oldsmobile Models water pump

We took our car to a mechanic because we thought it was leaking a lot of oil. He told us that it was the water pump leaking coolant and some oil due to the oil pressure switch and it would cost $465 to repair. I can get the parts and a technical manual for only $67. My dad has experience working on cars but I am wondering if this is a really huge job and would be better left to a mechanic?