Land ROI: rent vs buy

All three options are seen from the farmer's side, in one unit, with 30-day months. Income is what the land earns per day before the market fee.

after = income x (1 - fee%) buy per day = after (and you pay the land price once) rent per day = after - rent delegate per day = after x (1 - owner's share%)

Payback for buying = land price / buy per day, in days. Renting and delegating cost nothing upfront, so they pay from day one when the daily figure is positive, and never when it is not. Best is the option with the highest net result at the end of the horizon, on the numbers you typed. The scenarios table repeats the calculation with income 20% lower and 20% higher.

Nothing here reads the game or the market: the land price, income, rent and fee are yours to enter.