For the upteenth time, DONT TRY TO GET JACKPOT NINJAS.

The odds are so low its not worth the shot you will always end up loosing. For more information on the odds and the probability i invite you to look at the event feedback thread.

Anyways unless the odds are published only go for items who have a fixed value. In the forums you can find the avreage cost/frag for any ninja or item in almost all events, if you ever decide to spend in this game again make sure you will get the best vlue for your money.

As a side note, the mission boxes are excellent for f2p due to the huge aount of points you get for free, but imo they are not that good to spend on. Lucky board has much better returns for coupons spent and the lucky ninja packs have better rewards overall.