Smartmoney, whose year end stock picks killed me a few years back, put together some good charts on common household items that you should be buying generic. Their analysis is based on store's in New York, however, my wife confirms that these similar to what she sees in the Chicagoland area as well.
As shown, over-the-counter medication is where you'll find some huge savings:
They also detail fruit, pantry staples, some spices and canned vegetables. If you are cheap, broke, or just frugal...view the charts at Top Five Items to Always Buy Generic.
Items to always buy Generic



