So many people just rip it off.
There is an article in the Hartford Advocate this week about ASCAP cracking down, and actually lurking in clubs and charging them usage fees for the live music bands perform.
If you want to be totally safe, check out this site. They have a very liberal usage policy, and you can download royalty-free music for just about anything, at varying costs as cheap as three bucks. I've used them to buy soundtracks for some of my animations and commercial jobs. Oh, and good luck to your son! Cool! Maybe he can make W disappear for his finale!
http://www.opuzz.com/.