Our latest Freakonomics Radio episode is a rebroadcast called “How to Save $1 Billion Without Even Trying.” (You can subscribe to the podcast at iTunes or elsewhere, get the RSS feed, or listen via the media player above.)

The gist: Doctors, chefs, and other experts are much more likely than the rest of us to buy store-brand products. What do they know that we don’t? And if we all did like they do, how much fatter might our wallets be?