I've said this before, and I'll say it again. I would be willing to donate on a monthly basis like I do for NPR. And I don't need to get anything for it. Seriously. I want my badges and my followers to come from the content I provide, and links that I share. I imagine that if the "active users" donated $1 per month, you'd have more than enough to pay for servers and some more stickers and stuff. I know that model will never pay the team a salary - but it would ease/remove some of your OPEX. I like hubski a lot. I come here for FREE? it's crazy and almost unthinkable. I would gladly pay for what I feel like is a service. And some day when I no longer find it useful, I would stop paying and stop logging in... but I don't see that any time soon. As a side note - for the love of all that is decent and holy, please don't use paypal. I love me some Elon Musk - but I seriously hate me some paypal fees. There must be a better way.
I really like the NPR analogy. They manage to support themselves (in some places) entirely on donations and provide extremely high quality programming without denying any kind of "premium content" to non-paying listeners (no, WVYA, two CDs of classical music isn't "premium content," I'm donating because I like your station, but thanks.)