For the time being steam is out of the question, and there seem to be nothing that would change devs mind about it
Besides - if you want to support the dev, you can sub to him on SubStar, even for a month or so, as that way you'll actually provide support, so he can continue his work
Buying the game after it's been released isn't much of a support, to be honest, rather an obligation to pay for a product to be able to use/play it and so far you're playing it for free