Billboard/Bus Ad Campaign?

OK, so I'll start. Is there real interest in doing an atheism/agnostic/naturalist/skeptic ad campaign for the Capital District?
 
I'd love to see it happen, but we're looking at a few thousand dollars each for either a bus or billboard. Before we spend that kind of money, we would need to make some important decisions. For example:
 

• What would the desired results be? (i.e. recruiting, informational, etc.)
• Would this be effective as a one time deal, or would it need to be an ongoing campaign?
• Is a single ad worthwhile, or would we need to mount a full spread of media to get results?