Most People are aware of the local feed stores and other outlets that have taken the base corn product and turned it into a commodity such as deer feed. This is a little like buying bread instead of the wheat. For the best price, you can contact your local Corn Growers Association and find out where the local corn distribution center is (such as Cargil) and find out where to purchase corn direct.
Stored corn is supposed to be at 15% or less moisture. the elevators blend dry corn and wet corn sometimes to get an average of 15%. This could mean that one time you will get less than 15% and sometimes it could be 18-20% moisture. Ideally, 11-12% moisture corn is the best and it will give you app. 7,500 BTUs per pound . Corn hybrids that are high in sugar will give you higher btus. Stay away from wax content corn and do not burn treated seed corn.
Properly dried corn can have up to 8500 btu per lb. Unlike Pellets, corn is not sold completely dry and so yields an average of 6500-7500 btu per lb. due to Moisture Content - this is 10-20% less than the same weight of wood Pellets.
Good links on Corn Fuel - Michigan Corn Growers Association Heat Site: