BOSTON -- If you've never thought twice about throwing a bag of lettuce into your shopping cart at the grocery store, maybe you should.

“It’s more expensive to buy the bagged lettuce," said Diane Murphy, a frugal shopper who is dedicated to feeding her family of three plus the family’s pet cat three meals a day for around $100 each week.

Feed A Family For $100 Per Week

Bagged lettuce can cost $2.50 to $3.50, while an unprepared head of lettuce costs $1.49, and contains much more than the 8 to 12 ounce bags.

“It's about the money, and the less I spend at the supermarket the more we can spend on other things,” said Murphy.

A self-described “Yankee,” Murphy said she spends about 10 minutes before she goes to the grocery store checking the online circular. Then she plans a week’s worth of meals based on what is on sale. Her meals are healthy and filling, she said, not cheap boxes of macaroni and cheese.

“We do eat well. Last night we had London broil on the grill with fresh squash. Tonight we'll have chicken piccata because the chicken tenders were on sale,” she said.

Murphy buys real, not packaged, foods as often as possible and cooks meals herself to save money. This week’s on sale items include cantelopes and round roasts.

“One was pretty large, so I had the butcher cut it in half so that would be three meals for us,” she said.

Murphy also stocks her basement pantry and freezer when the foods her family enjoys go on sale. “I buy frozen fruit for when the fruit that I like is not available at the right price.”

And she doesn’t buy a lot of snacks or costly beverages.

NewsCenter 5 found more smart tips for saving money at the food store. Generic, store-brand items are often the same quality as name-brand items, though they cost less. Another way to stretch your dollar, make sure you’re not paying more for packaging.

Compare labels to get the most product for the lowest price, like buying popcorn kernels instead of microwave popcorn, or spaghetti sauce in a can instead of a jar. Canned sauce can be up to 50 percent less expensive.

Murphy estimates that she saves about $50 a week by taking a few minutes to plan before she goes grocery shopping, which adds up to $2,600 a year

She also relies on coupons -- from the newspaper and online -- as well as recipe Web sites that allow you to type in what you already have on hand, to see what recipes you can make without buying additional products.

“It does take some organization, but it's worth it,” she said.