Hi

In order to acquire 80 frags for Kakuzu Earth Grudge from the Sakura Gift event you will need around 3,200 points (1,067-1,600 foodsacks) [10,670-16,000 Coupons/Ingots]

However since you can redeem frags from the Time-Limited-Shop as well with points based on your spendings of INGOTS as a rebate then you should be able to get half of the frags from Sakura Gift and the other half from the Time-Limited-Shop so the total price would be 8K Ingots.