After some hunting around the site and using a dashboard widget to translate, I found an emial address for the ferry company on their web site. It was not under the carefully labeled in english – Contact Us, button, but on the prices page. The price does not include the 1,000 won for something I cannot remember or the 7,000 won fuel surcharge.
Ferry chage: 일등실(FIRST) 원화 165,000.
Extra charges: ￦1,000원과 터미널사용료 1,600 유류할증료 7,000원 별도
email: pass@dainferry.co.kr