Working capital is not a third kind of cost. It is money that must sit ready because spending comes before earning.
Count the days. ICAR-DMR states that one tonne of dry straw gives fresh oyster mushrooms in 45 to 60 days, while the same straw taken through button compost needs 80 to 100 days including compost preparation. Your first rupee arrives at the end of that stretch. Then add the buyer's credit period, often another week or two.