How do ads make a site more mainstream? I don't understand. Maybe explain better? I apologize for being dense.

Are you talking about buying ads (for this forum) on other sites? Just to get people here, looking, and more interested in the vehicle...and prospective buyers? That doesn't sound like a bad thought...but would require MORE revenue from current scarce membership to draw interest. Maybe that's an option for the site-owner to "invest" hoping to get new traffic?