That's a ton of money, but those things can carry more than 13 tons externally. That is an important ability, because it means they can carry not only heavier artillery, but LAV's as well, which weigh slightly under 13 tons. The Marine Corps is a forward-deployment force, and the ability to lift large amounts of equipment into areas, and then support them with heavy lift capability, is very significant.
Frankly, I think those things will see a lot more actual use than F-35's.