I've been paying a Meetup groups fees for over two years because I think it's good to keep the group going and not have it worry about generating funds, and I can afford the $180 a year. We do sometimes put out a collection jar during a meetup which tends to bring that down to about $130 a year usually, but I'd still pay it even if we didn't get any money, just so people have a group where they can post local geeky activities on.
I met the vast majority of my current friends through that group, so I feel like it's worth keeping it going.
I see a lot of other local Meetups shutting down after Meetup.com raised their prices last year, though. I'm a little surprised they're actually making more money after doing that, because I saw a loooot of groups shut down because of it.