"do people really attend such events where libations are not available?"

Yep. There is a sizeable hunk of the population who hate bars, hate drunks even worse and actually enjoy listening to and/or playing music in an atmosphere where the music doesn't have to fight to be heard over bar racket. I know 'cause I'm one of 'em.

And, Clinton, when you're price haggling over what you'll be paid for running this open mic, make sure that stipulations are made about what happens if participation is slim. If hardly anybody shows to play, will you be expected to take the stage to keep some entertainment going? If so, will you be paid more? I've emceed open mics before where I've had to play for two hours because only a couple of people showed up. I wasn't getting paid anyway so it wasn't an issue, but if I were being paid one price to emcee and another to perform, I'd make sure I got the performer's price if that's what I wound up doing.

Bruce