We've baled corn stalks too. Very hard on the baler, but that's beside the point.
For a 4'x4' round bale of corn stalk we've gotten from $4-$12 in the past couple years which would be about $16-$48 per ton. The stalks are used for bedding or mixed in food rations for cattle and dairy.
Shipping costs get to be a factor quickly when hauling round bales.