the farms calculate the costs on the overhead of the farm only so if you got about 1 million of crop max collected per year in a crop unit by a monthly farm overhead of $8.000 it ll be 8.000 x 12 / 1.000.000 - $0.096 per crop. to get the real price for your stuff you d got to take some sort of sprea...

you can add graphs to see either the monthly revenue/profit or units sold on top of the product picture, to turn that on you got to look at the far right side of your product picture list inside any firm theres a graph symbol ... click it. marked red on picture below for numbers, i made up a little ...

... I'm impressed that you go to the effort of keeping a spreadsheet to calculate unit costs! If I keep playing, I'll probably do the same myself, but I really think the number of units produced per month (or day or whatever time period) by functional units should be given by the game. I'm struggli...