Why is Dong 'e Ejiao so expensive?

The cost of donkey skin is getting higher and higher, and all the processes need a certain fee. Another thing is that people are now paying attention to the health of life. All the prices are obtained from the market, and the daily intake of donkey skin is generally 3-9g. If calculated by 2000 yuan and 500g, 1g is 4 yuan, and 5g supplements 20 yuan every day. It's not worth it.