It's hard to see paying extra for a diesel engine unless you really, really need the towing power. The fuel is higher, the initial price is higher, repairs could be higher, gas engines last a lot longer now and don't usually need a lot of maintenance. The traditional advantages of the diesel are getting smaller or have vanished.
If I were looking for something to reduce the price of a new truck, choosing between 4X4 and a diesel for example, is a no-brainer where winter counts. The only reasonably priced new pickups are the base model, standard cab, 8' box - which few people want or can use as a family vehicle.