Thanks for all your work, I make sure to reference AppyBuilder as my App Inventor platform of choice in all my posts about app development. I’ll definitely donate as I am able.
Might I suggest that you think about doing some crowdfunding campaigns for major features and releases? People really like having their donations tied to something tangible. You can “self host” a campaign and not have to give up 30% to a platform for more prosaic projects, although I do think there’s value provided through exposure on a hosting platform like IndieGoGo in some cases.
You might also think about a focused word of mouth driven social media campaign, profiling app developers using your platform (for instance) and highlighting apps developed with it. Is there a list of such available?