A commercial plan that begins with a species is a plan looking for a market. Turn it around. Walk the mandi, the cold store and two hotels, and write which mushrooms already move there, in what pack and at what rate.
If only button mushroom sells in your town, an oyster plan must include the cost of creating demand, and that cost belongs in the project. If milky mushroom already arrives from a neighbouring district each summer, you have a price benchmark and a competitor.