If you want something for free there probably are other alternatives.
Sorry, but this idea of 'what costs money isn't a viable option' just puts me off more and more.
Esp. if the price level for something great is that reasonable.
You're under no obligation to choose a license. It's your right not to include one with your code or project, but please be aware of the implications. Generally speaking, the absence of a license means that the default copyright laws apply. This means that you retain all rights to your source code and that nobody else may reproduce, distribute, or create derivative works from your work. This might not be what you intend.
Even if this is what you intend, if you publish your source code in a public repository on GitHub, you have accepted the Terms of Service which do allow other GitHub users some rights. Specifically, you allow others to view and fork your repository.
https://help.github.com/articles/licensing-a-repository/
And the TOS say:
We claim no intellectual property rights over the material you provide to the Service. Your profile and materials uploaded remain yours. However, by setting your pages to be viewed publicly, you agree to allow others to view your Content. By setting your repositories to be viewed publicly, you agree to allow others to view and fork your repositories.
So the source is there....then surely it must be open source?
Also the devs are very nice and you can test it as much as you want.