If you want to take this coat ,you'll have to pay---30 yuan.

1.D.another,意为：多加,另多付
2.例子：I have three apples.I need another two,(后半句意为：我还得多要两个.)
如果用 more,句子得改成：
...,you'll have to pay 30 yuan more.
或：
...,you'll have to pay 30 more yuan.