This was posted to Wise Bread, and reposted here:

Pick around a dozen key purchases of (relatively) nonperishable items like canned goods, dried pasta, some grains, sauces, frozen items, etc. Know the prices. When you see a price drop, stock up.

Then, over the course of the next few months, eat through the stock.

The weekly shopping trip should focus on getting the fresh foods that can spoil. Buy in season, and on sale. During the summer, eat mostly fresh, but stock up. During the winter, eat through your stock.

During the winter, add chiles to your diet. The extra spice will make the food taste better. Just buy two or three serranos or jalapenos, and add a couple slices to your cooking.

Buy junk food at the dollar store, or the Big Lots. There, you can get things for a dollar.

Shop at the bag-it-yourself stores in working class neighborhoods. They often have lower prices on most items. (Again, don't assume they're cheaper across the board.) Check to make sure the vegetables are okay. Unfortunately, in some stores, they are not that good; but at others, they're fine. (They may also double as ethnic markets, described below.)

If there's a spice rack with bagged spices, the prices are much lower than the bottled spices. Usually, an ounce of spice is around 70 cents.

People in big cities can shop at ethnic markets. Asian markets tend to have the lowest prices on vegetables. Watch out, though. They buy food that's riper, and won't last as long in the fridge. So you have to eat it soon. The 50 cent lettuce isn't a good deal if it rots. The $1.50 small bok choy is a great deal: I could eat the whole bag in one day.

Ethnic markets also have much better prices on sauces, breads, spices, and the like. The local supermarket has pita bread for over $2 a bag, but the Armenian market has it for under $1. Oyster sauce at the super was nearly $5, but at the Asian market, it was $2. A "specialty item" in a mainstream store is a common item at an ethnic store. (The reverse is also true!)

Learn to make dishes that use leftovers: sandwiches, fried rice, ramen, soups, small pot pies, scrambled eggs, burritos. Keep the starches like bread, rice, pasta, and tortillas on hand, and make the filling or soups with the chopped up leftovers. Learn to make some extra food for dinner so you'll be able to make these dishes for lunch.

Phil Brewer had a great article about shopping as a kind of investment. It's true. If you spend, say, $2,500 on food each year, and can shave off 10% of the cost, you've just "made money" - saved $250. That's equivalent to earning 11% on a 1-year CD valued at $2250.

Last I checked, there was no such thing as a 11%, 1 year CD.