When I got my Cummins Dodge 3.5 years ago, diesel was running about the same price as regular, sometimes lower. But, as fuel prices went up, diesel really went up. Gas prices have gone down, but diesel has stayed high here, in some casses 10 cents or more than premium.
Still though, if I had a 3/4 ton 4x4 gas pickup with 4.11's, I would get a lot less mileage than I do in the equivilant diesel. It evens out better on the side of diesel. But, it was an even better deal a couple years ago...