Since I'm not sure exactly what the fishing rate was for success I estimated between 85-90% I put a chart for both, of the amount of coupons you would need per level range based on exp required to level, and based on how much $$ it will cost you based on ncoin/$*coupons for the pack you buy.
https://s13.postimg.org/3ns91dztj/Heine_Fishing.png