Okay, so from my perspective, I believe that sometimes Fuku is worth it till a point, like 5k or 10k. This one would only be worth it if you could spend for all the rewards, like 30k. Unfortunately because you don't have 30k, and in my opinion the only event worth of coupons is lucky stars(but even this one is so and so), I would advise you to save more and wait for better rewards.

Power wise I would recommend spending 10k for training potions in lucky stars if you can afford it. I disagree with comment above. Do simple math - would you rather get 3x 10k rewards, or 30k reward? Don't be fooled by adv. threads - they are used for the most overpriced power feature in the game.

Although you can never go wrong with saving. ;)