Koi: The seller usually tells you if they ship to US, though unfortunately it is in Japanese. I have yet to see a seller say they ship int'l. Sorry
Reizo: If you plan to import, it'll cost just as much as, unless you're planning to buy in bulk. BTW, where are you pulling the ISBN's from? I usually find manga easily on amazon.co.jp through ISBN. They've got a great search tool.