THR did their homework on this one, going as far as to reveal monetary returns (which to my knowledge no podcaster has made public before). 

The beauty of the podcast is its simplicity: Anyone can purchase a microphone and mixer, and the cost is nominal compared to a traditional radio program. “With an investment of $700 to $1,000, you can make a show,” says Maron, whose podcast regularly charts in the iTunes Top 10 and charges $1,000 to $15,000 per sponsor. 

…

In contrast, Carolla also works from his garage — “He’s got a bunker!” mocks Maron — but he employs 18 people, from “$10-an-hour guys” to those “making six figures.” “It’s a business,” says Carolla. “Madison Avenue and corporate America are already involved. I don’t know how to define success, but I can tell you that 18 months ago, companies like Nissan or LegalZoom didn’t exist in our podcast world. Now they’re in it in a big way, and other companies are coming on board.”