Why so expensive? Take ‘California Gurls.’ It features Snoop Dogg. He’s pricey. And the producers on the song — Dr. Luke and Max Martin (among others)— who charge around $100,000 per song. And there are 12 tracks on the album.

Then there’s Katy Perry’s advance. “That advance could have been perhaps a million dollars net, maybe two million — I can’t say for certain,” Tavel says. (…)

Next expense: Getting the album played on Top 40 radio. Andy Tavel says it could cost up to $250,000 just to get the first single played on radio — special promotions, free merchandise, and presents. (…)

Tavel figures the album cost the label somewhere around $4 million.

They made all that — and much more — on the sales of Katy Perry singles. (…)

Here’s what Katy Perry sold in the United States: 2 million albums and 25 million digital tracks.