I may be the only law prof to have run a radio ad for my firm (technically, it was for class members in specific class actions), but you’d be surprised how low-budget an affair it was. One time, I just went into the radio studio, they recorded on a cassette tape me reading a script I’d written myself; the other time, they asked if I want any background music – I said yes, and the result was cool but made it sound like I was a pimp in a 70s movie with theme music.