I really need an alternative for grit. A 5 lb bag is $90 here in Japan. 
https://www.amazon.co.jp/-/en/Manna-Pro-Poultry-Grit-5-Pounds/dp/B000QFSAJW
Can't even find a domestic supplier.

https://www.amazon.co.jp/-/en/Manna-Pro-Poultry-Grit-5-Pounds/dp/B000QFSAJW
Can't even find a domestic supplier.