depends on what car id say. They need a box built. lol. Deadening is going to be a pain and take time. id do ~20 an hour. So figure 1 hour running wires and installing the stuff. and 2-3 hours deadening. Depends if there a friend id say 60-80 or someone random 80-100.
I told him $150, he just called and told me that he actually needs only the rear deck done (subs are IB, going on the rear deck), and the car has the battery in the rear so this is going to be super easy. When he gets here I'll only end up charging him $100.