That is the big "gotcha". It is currently subsidized. The actual production costs for E-85 from corn and sorghum (per unit of energy) is easily triple that of petroleum gasoline. This is a re-hash of the "gasahol" crap from the early eighties. Just another additive (like MTBE and the detergents like phosphorous). Engine technology is much better today, but E-85 is much less efficient than gasoline. I do not remember the exact percentage, but 87% comes to mind. I will google it.
E-85 is a real bargain now but once there is a demand for it, I would bet the price will be right up there with regular. Sure wouldn't want the oil companys to take a beating on it.