I assume you raise it, harvest it, store and dry it, then transport it to the elevator. I don't know if you shell it or not.
From the elevator it is transported, stored, processed, packaged, transported again, warehoused, and stocked on the shelf. Various overhead and pay somebody to manage the cash register. I would not be surprised if there were a few taxes paid along the way. For a relatively small package, a mark-up of 4 times your selling price is probably not that bad. There area lot of people supporting their families along the way.
If you can get it ground to the consistency you want for cornbread for less, absolutely a good way to go. Good luck finding a mill.