Those numbers are only semi realistic. Your local hardware store probably only has sweet corn seed (what I priced) which will not yield as much as field corn, but it is worth more if you sell as sweet corn not field corn as most farmers are selling corn. I have no idea how to account for this important factor.

Mike Bloomberg hasn't heard of fertilizer, so I didn't bother pricing that, but to get the yield I quoted every year you need to replace what the corn takes out of the soil and that means fertilizer of some sort.