Please feel free to edit this post, it's my first on Meta, and I always manage to unwittingly violate a few rules...
Have you guys considered linking up with professional bodies for these meetups?
I am a member of the BCS who have a lot of talks over the autumn/summer/spring period. It may be possible to link up with a group like the Advances Programming SG or even the BCS London Central Branch. They would probaby be happy to provide the venue, and mutually advertise. You do not have to be a member to attend, and they usually pay the expenses for speakers.Edit: and it's usually (free for BCS members | very cheap/free for non-members) to attend.
For the BCS (I'm not sure about other bodies, as this is the only one of which I'm a member) the format varies by group, but there's usually an evening talk, possibly followed by drinks and nibbles at the venue, and then a sizable contingent go to a local pub or wine-bar for a few more hours of putting the world to rights and discussing the latest in technologies.
I think that linking up with these events could be beneficial for all involved as costs could be spread, and there's a guarenteed audience.
Does anyone have any thoughts on this?