Don't overlook the power of the Internet. Perhaps you could have someone make up banners for your Relayers to place on their MySpace and Facebook pages? I make banners for some independent bands regularly, and the impact they have had on gaining new fans and increasing revenue on CD sales cannot be denied.

I'd also see about getting it on TV if you have a channel that runs advertisements about things going on around town, or in the community calendar of area newspapers. A lot of television stations also have Community Calendars where they select events to promote on the noon news. Some have the option to add events to them on the station's Web site, and some require a postcard to be mailed in. I'd also see about getting time on the morning show or the lunchtime news to promote the event as it draws near.

Good luck!