Hi! The information below is based on the efforts of the Community Helpers in Discord.

For every 20 Coupons/Ingots = 1 spin

Every 1 spin gives an average 2~3 Lucky Stars with a Maximum of 500 spins a day

For additional information, you can find it in the "event-information" section on our Discord found here.

Regarding the inquiry of why this information is not being posted on the forum. The reason is because the information above is courtesy of our Community Helpers. This is not the official pricing as it is based on players. Hopefully this helps!