What country are you from? Gamersgate offers a variety of payment options for different countries (I have neither a Credit Card nor a PayPal account myself). Also you can download the game as often as you like, in case your computer screws up. Same goes for Steam. Considering that a disc can get scratched, this is even safer than buying it in a box.
Also I never needed a credit card to buy stuff from Amazon...again this probably depends on the country you're in?
Quote: And not to mention - I do not trust to order things from those sites. I know more than well the conditions of the products can variate.
...you do not trust Amazon to sell you a brand new copy of Amnesia in a box that works? I don't get it.
Quote: I want them to see it as a hardware... internationally.
It is available as a disc and yes, internationally - just buy it off Amazon. You can't expect a small indie studio like Frictional to make their game available in every Game Store in every City around the world - its simply too expensive for them and the small number of additional customers they might gain can't make up for that.