Are you going for wild west because you already got the others? and what is you BP by the way?

My suggestion is that dont spend your coupons directly on buying magatamas, refine runes, and charns. Wait for events where you can redeem them like those wheel events(but please dont fret when you dont get the jackpot ninja on those wheels coz your main priority are those power items). Focus on Mt. Myoboku gift up to map 10 coz they are a very good source of power. Clothing is also very good, you can opt to get them in batches instead of in just 1 go, and for me, the best clothing to get are Anbu and Exquisite.

no i only have fukorokumaru and the samurai, 70k bp

Hi there! If you wanna get some new clothing and at the same time, you want to gain power .. then i will suggest to get the Anbu Cloth or Exquisite Silk Cloth first, because that two clothing can give you around 1k+ power .. Wild West Clothing only gives 460+ if im not mistaken, same goes for the Sai Uniform Clothing .. And for the rest of your query, just like what the other people said, don't buy directly, wait for the events where those items are available for redeemables ..

yes, but kimono and wild west usually cost 2500-3000 coupons, while anbu or exquisite silk cost 5-6k so is normal they grant half the power...