I cant speak for the price but I went through a few open houses by the same builder in the same area and some were foam and some were fiber. The foam houses were significantly cooler, especially in the garages and attics. The houses with foam were cooler in the attic than the fiber homes were in the garage. I would say if you really planned on it being your last home it would probably be worth doing the foam. I would want the foam and might even consider ducting the garage for HVAC.
Speaking of cool attics, if I went with foam, I probably would elect against cathedralization but I would definitely get my HVAC unit within the conditioned space.