I would save your scrolls or use them on tendo, tendo ninjas are "better" than the ones in the seal treasure.Most ninjas that you pull from the treasure boxes are useful in some ways, most i just use for the survival trial or the Matsuri. At some point in time you will get Orochimaru (70 Elite Instance), but i still think you have to spend money to get Iruka. You could save them all up and once you hit 70, spen them all on that treasure.