Per Nachnahme means, that you pay the ordered item when it is delivered to you, so you pay the postman. But as far as I can see on the website that system is only allowed in Germany. So you have to order by Vorkasse, which means you pay ahead. Usually that works by paying it in onto their Bankaccount, which will probably cost you some money again. I remember, that when I ordered from Germany I usually had to pay about 5-10 Euros for each transaction I did onto an account in Germany. Maybe it is possible though to do it by Credit Card or PayPal, I didnt check the site overly well.
But I think you have to at least have to calculate 17 Euros for the shipping. But as I said it even is possible that they will change that to more if you are ordering something really heavy. Like when I ordered a 20 liter Barrel of Mead from Germany, it was so cheap, and the shipping was only 13 Euros. Suddenly I got a mail from them though, that the shipping is 39 Euros, because Switzerland isn't in the European Union and so it costs more. :/ Well I ended up cancelling the order.