George Clooney chats with Stephen Colbert on the premiere of "The Late Show with Stephen Colbert," Tuesday Sept. 8, 2015.

Stephen Colbert's tenure on "The Late Show" has officially begun. But, it wasn't just fans of "The Colbert Report" eagerly awaiting the comedian's debut: Brands have been lining up to get ads.

A source with close knowledge of the situation said that 30-second ad spots during the premiere were going for about $175,000. CBS did not immediately respond to a request for comment.