The stores that sell almost-expired food, dented cans or torn bags, local farmer over-production, that sort of thing. (And FWIW, only one can in a flat has to be dented for "the powers that be" to deem the entire batch unfit.)

My most recent good buy has been repeated three years in a row here. It's May, and the local store is selling one-pound bags of black-eyed peas at the discount price of 3 for $1. New Year's Day was 5.7 months ago and the bags are marked 2012. It's a seasonal product, like Thanksgiving cranberries or Christmas and Easter candy. The peas will be good for 4-10 years, at least, if treated properly. Given that every other grocery store in town still has black-eyes at anywhere from $1.29 to $2.29 a pound, three pounds for a buck is ridiculously cheap.