Ok, so I did the math. A sample calculation is provided below, in case you want to check it. I didn't feel like writing it out for all the rewards, so just look to the bottom if you want to see the final price range. K? K.
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Sample Calculation
This is for Sailor Sakura:
She requires exactly 1600 points to recruit her. Each key gives 3-5 (6?) points. Each key costs 10 coupons.
You get 1 free pull everyday, and the event lasts 7 days, including today. You can get 21 to 35 points.
You c*so get at most 10 keys from instances. This equates to a further 30 to 50 a day, or 210 to 350 points by the end of the event.

So, you'll have made 231 points for free if you're extremely unlucky or 385 points if you've been blessed by RNGsus.
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At this point, you have to make this difference up by buying keys.
If you are unlucky: 1600 - 231 = 1369 points. --> 1369/3 = 457 (rounding up) keys. --->457*10 = 4570 coupons/ingots in total. Assuming you spend the 3000 ingots, you get 23 more keys, which, if you're unlucky will save you just about 230 ingots. 4570 - 230 = 4340 total.
If you the luckiest m*ive: 1600 - 385 = 1215 points --> 1215/5 = 243 keys. --> 243*10 = 2430 coupons/ingots in total. Assuming you spend the 1000 ingots, you get 8 more keys. This, if you're lucky, will save you just about 80. 2430 - 80 = 2350 total.

So it will take anywhere between 2350 coupons and 4340 coupons in order to recruit her as a 3 star.
Just to go the extra mile: If you were to pay real money for the whole thing, it'd cost you between $47 to $87 dollars. Considering RNGsus loves nobody, if you want to buy her straight up, it'll probably cost more like $75, since you're more likely to get 3 points per key than 5. The above is just the absolute min and max you'd have to spend.
0o0o0Prices
Congratulations, you probably skipped the math. Who needs that crap anyway? Well, on we go. The assumption is that you have 0 fragments of any of these ninja. Also, prices are rounded up, as you can't buy $0.50 worth of ingots.
GNW Kiba: 2 Stars: -50 to 430 coupons --> $0-$10. Probs like $6. 3 Stars: 1150 to 2430 coupons --> $22-$47. Probs around $36ish? 4 Stars: 3470 to 6350 coupons --> $70-$127. Probs around $110ish? 5 Stars: 8120 to 14200 coupons --> $163-$284. Probs around $245ish?
Pain : 3 Stars: 2110 to 4030 coupons --> $41-$76. Probs around $62ish? 4 Stars: 5480 to 9800 coupons --> $110-$196. Probs around $167ish? 5 Stars: 12680 to 21800 coupons --> $254-$436. Probs around $375sh?
Sailor Uniform Sakura: 3 Stars: 2350 to 4340 coupons --> $47-$87. Probs around $77ish? 4 Stars: 6200 to 11000 coupons --> $124-$220. Probs around $188ish? 5 Stars: 14200 to 24334 coupons --> $284-$487. Probs around $419ish?
Kirin: Gold Summon: 8830 to 15230 coupons --> $172-$300. Probs something like $255.
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EDIT: Please know that this assumes that you can get all 10 keys everyday, and some people seem to having trouble with the drop rate, so you may spend more than estimated. But you should never spend more than the maximum amount I calculated. RNGsus isn't thaat much of an *.... right?

EDIT: Calculations were changed, as per requests. You will receive the recharge bonus keys depending on how much is needed to be spent. Spending over 1000 nets 8 more keys and spending over 3000 nets 23 total keys. I did not apply 23 keys to everything, because I assume you are only pulling for that 1 character, and spending another $40 to save yourself about $3 is dumb. Anybody who is going to spend that much anyway, just take off 3 dollars to any price except GNW Kiba's 2 star recruitment, where you take off $5.
EDIT: 4 star and 5 star data was added for those crazy *s out there.

This post was last edited by DraconusNex at 2016-10-21 10:30