I stand corrected. After checking prices at 2 of the larger Dodge Ram dealers in our area, I found the premium for the Ecodiesel is not as much as I thought.
Half ton trucks that have identical equipment packages, are selling for only $8900 more, diesel vs. v8. One dealer has 159 half ton Rams in stock, so it was pretty easy to find identical trucks to compare.
These were not sticker prices, but negotiated selling prices, with no trade-in. Sticker prices show a larger premium, usually about $10,000 difference.
Maybe the higher prices here are due to the huge demand for diesel pickups in this area.