Catalogs:
http://nissr.cc/nikke
http://my.jiankj.cn:81/Games/NIKKE/index.php
http://mxwy.ltd/index/slnvnj/
http://bssy.top/index/nikke/
Please visit one of the above catalogs to choose an account. Then, message the seller through the website's chat window for the price.
Price depends on the account selected.
Make a purchase with quantity set equal to the price of the account you're getting.