For anyone interested:

you can get for free (assuming 1050 points), then cost per frag and cost to recruit/upgrade:

30 sailor sakura frags - 1050pts - then its 70cp/frag - 3500 to get missing 50 frags

11 masked man frags - 990pts - 180cp/frag - 12300 to get missing 69 frags (rest of free points included in cost)

11 rasa frags - 990pts - 180cp/frag - 3300 to recruit 2* / 6900 to upgrade from 2* to 3* (rest of free points included in cost)

17 charm packs - 1020pts - 120cp/pack

4 tsunade frags - 864 pts - 432cp/frag - 32460 to get missing 76 frags (rest of free points included in cost)

To summarize: dont buy charms except for free points. masked man seems okay, sailor too. Rasa last time he was available was for 110/frag, tsunade was for 430/1 or 510/1(not sure which was tsunade and which kyuubi), either way its slightly better than last time // anniversary events

Keep in mind those prices arent including anything from boxes. You can decrease overall price by ~20% because you get useful stuff like medium threads, medium refines, cave keys, mangatamas, scroll frags, coupons and a chance to get a ninja. Players that are past medium thread/refine level should wait for other event to get those ninjas if they want to minimize the cost.