In the last event he was in you could get half of Kakashi for free and to finish him was only 1k coupons, it was the Naruto Birthday Ramen event so this seems very overpriced to me and it's even with discount.

But you also mentioned that you do not wish to change class and stay water, so 1010 is the one to go for. She is actually nice for water mains, i don't see anything that Kakachi can offer water mains, he is mainly for lightning and earth mains.