Sound like you and the dairyman need to have a talk. Right now he has a sweetheart deal where you assume all the risk. That level of risk should come with a good return, now is not the time to be setting prices, that should have been done when you agreed to rent his ground and sell him feed. Contract may need to have a per-acre minimum value added.

You might be better off just doing custom farming for him, charge by the acre or hour and let him have the risk. I am a dairyman, though I raise our own feed. This deal has the potential to be very good for the both of you, but it sounds as though he is trying to take advantage of you.

"Here", in a normal year, with decent yields, CS has been selling for $25/T or so delivered to the storage area, or about $16-18/T standing-this was last year, haven't heard any prices this year.