You'll likely get a lot of useful items for your coupons, the Rune Packs are worth it (even if its just for the summon points), but you won't be able to get all of a character. You can, however, make good progress towards a character with that much, and you c*so possibly earn something good from Lucky Ninja Pack.
However, I wouldn't say deplete all your coupons if you have no way of getting them back over time easily (Jonin Medal), events like the Key Treasure have good discounts and you may be able to get a 2* Iruka if you don't have him, or something else good.
This post was last edited by Amadeu at 2016-11-7 09:34