I would definitely scrape together funds to pay a monthly fee (like Reddit Gold, or perhaps a subscription sort of thing) if it would help keep Hubski online and thriving. The community is so thoughtfully laid out and managed, that I'm sure whatever mk has planned will be perfect.
I think there's also potentially value in making heavy-use of the features a paid-for feature. For example, if non-paying members were not allowed to submit more than 1 post in, say, a 24 hour period, that could: (a) encourage careful selection of what to post, reducing the "fun" of posting image memes or trying to "karma-whore" (b) add perceived value to the cost of a subscription, potentially increasing uptake I know that's a controversial idea, but honestly: I'd be willing to pay to get better-curated content, and this kind of move might do that.