Jingles are, by a wide margin, the most expensive copy I do.
Why?
Because they're worth it.
Jingles stay in people's minds forever. If I were to hum a few bars from a well-known jingle, classic or contemporary, your average person could finish the tune. Unlike slogans and logos and especially annual ad campaigns, jingles are a buy-once cry-once way to consistently generate a stream of leads that result in profit. Get a jingle means, to quote the kids, you're sitting on a mill.