I'm still thinking on the good solution. On steam I cannut use "donate like" payment method. So I have to sell it for 1~3 dollars. Beside that, that would be strange if you can download the same game for free which is 1~3 dollar on steam. The 0.88/0.89 versions are almost completed games whit some minor bug. Sooo probably these will be available for free in the future too and if somebody wants the v1.0 and same new feature, that will be on steam.
...but I listen every solution idea! ;)