In my opinion, in a 3/4 ton truck, cost of ownership of a gas vs. diesel engine is basically equal.
I drive a diesel mainly because I pull heavy loads fairly often. But, I have and I will consider a gas every time I buy.
Diesel engine vehicles cost more up front, but you recover a good bit of that at resale.
Diesel fuel cost more at the pump, but you generally get better fuel mileage.
Diesel engine maintenance cost more, but you usually do less maintenance.
I own 2 Isuzu NPR trucks, one is diesel, one is gas.
I own 2 - 3/4 ton pickups, one is diesel, one is gas.
I say the cost of ownership of gas vs. diesel is a wash in the long run.