In the movie Three Billboards Outside Ebbing, Missouri, Mildred Hayes, played by Frances McDormand, rents advertising space on three billboards located - as you would expect - outside the town of Ebbing in Missouri, for $US 5,000 per month.
Your advertising billboard could also be visible in Ebbing, Missouri, and for that matter anywhere else in the world with a mobile phone signal. Provided, of course, the viewer can find it on his or her smartphone.
This is where a powerful domain name would be really useful! It doesn't have to cost $5,000, either.