IDK how much one of those billboards with the rotating ad strips that come together to make up and ad would cost to rent out ad space on, but maybe advertising positive affirmations would probably be the best I can do with that amount. At least from what comes to mind right away. I live close enough to one at a busy intersection that I could watch people and see how they react to them.

As much as I hate ads and billboards, I will admit they can be effective considering I always watched that specific billboard growing up whenever I passed by it.