Is milky mushroom profitable and who buys it in the market?

Milky mushroom can be profitable, helped by its better shelf life and its ability to grow in the hot season when button cannot, but the market is less developed than for button, so you must build demand. Buyers include local vegetable markets, hotels and restaurants, and some health conscious city consumers, but awareness is lower than for button mushroom, so you may need to educate buyers and offer samples at first. Because it stores and travels better than oyster, it suits slightly distant markets. Profitability depends on your yield, your selling rate and whether you can sell consistently, so I would not quote a fixed income. Start small, fix a few buyers, learn your real costs through one crop, and expand only once selling is steady. Check local demand and prices with nearby growers and your KVK before scaling.