Also, I think that you really have to examine two factors when considering radio ads.
1. What are the demo's of the people visiting your haunt.
2. Are they active radio listeners and if so, what stations.
The age of the person visting your haunt may determine if and what stations that you spend money with. If you have a young 13 - 22 demo that only listen to a few stations, but are more into Facebook and streaming radio like Pandora or the like, then I wouldn't buy the radio, but focus my ad dollars on social ads and new media. But if you have a large 19 - 28 demo that attend the local Univ and listen to the local college ran station the majority of the time, then it might be worth it.
The most important thing is to do your market research to find out who's coming to your haunt. That will tell you where and when to spend your advertising budgets.