Pre-sliced meats, bagged salads and chips packaged in handy snack packs all save you time in the kitchen, but they'll take a bigger bite out of your budget. Case in point: A head of green leaf lettuce at a New York City grocery store runs $1.99, while a bag of already-cut and washed lettuce from the same store is $2.89.
The lesson: You'll save money if you do more of the work yourself.
The same is true of processed foods. Instead of buying a jar of pasta sauce, you can buy a can of crushed tomatoes and some spices and make your own. And you might even cut some unwanted sugar or salt from your diet.