I buy games from GOG and pay with Paysafecard. I usually buy 5-6 games for the normal price of your game. I don't want to spend a lot of money because I never know if a game will work for me and if I will like the game at all. A demo version could change that. 9.39 Euro at GOG during a sale was still too expensive for me. You could offer the Linux version much cheaper, nobody uses it anyway! ;)))