Hi!
Since Sage Naruto is 45 points per frag and you need 80 fragments to recruit him, it means you require 3600 points. However, if you include the free ones you get every day giving a total of 1050 points. That means you only really need 2550 points.
Each box cost about 20 coupons/ingots which means if you don't have any sage naruto fragments to start with, it would cost you 5100 coupons/ingots to fully recruit him during this event!
Hope that helps!
~Jib