95 cummins needs injector pump...input please
 

I'm thinking of buying a 95 cummins single cab, auto, 169,000 miles, 4x4. It needs an injector pump. Truck is in good shape and he's asking $3200 for it. How much is a pump going to be for this truck? How difficult will it be to install? (I do all repairs on my vehicles myself) is 3200 a good buy considering what it needs? Thanks