So you divided each result 5 which give the value of each cave key as compared to a lvl1 rune since its the smallest increment of a rune you can get. Using the average we can than reverse engineer what the technical cost of a rune base on pull type. Some quick math gives the following: 1 pull -> 9.04 coupons, 10 pull -> 7.997, 50 pull -> 7.788 coupons. So the cheapest cost value of a max lvl rune is 5233.5 coupons per lvl 12 rune. So total cost to equip all nin with max runes is 418,682,.88 coupons if you used zero free sources.