I just attended my first WP Seattle meetup last month and was very impressed with the organization and attendees. Turnout here seems quite high compared to what you experienced -- 80 or so registrants on meetup.com, with probably 50 of those actually showing up.

The company I work with has sponsored food and drink at two meetups so far and will be doing so again next week. Sponsorships are a great way to provide some extras for attendees while keeping registration free and giving a local biz the opportunity to say a few words.