Posted by Elisabeth Leamy, Tue May 03 2011, 12:55am

Sometimes saving BIG money can mean knowing a bunch of little secrets

Sometimes saving BIG money can mean knowing a bunch of little secrets. Grocery shopping is that way. Here are a bunch of my favorite supermarket secrets that can help you bag a bargain on food, personal care items and household supplies.

Make a Top 20 List. You don't have to become some sort of grocery savant with hundreds of prices memorized in order to save at the supermarket. Just make a Top 20 list that is a combination of the top twenty things you buy the most and those that cost the most. You need to know these prices, so you'll recognize when a store is having a killer sale and you ought to stock up. Otherwise, it's easy to fall for a store's hype about it's discount, when it's really not that great a deal.

Limits = Deals. When a store advertises "Limit, three per customer," that's a great indication the price is near the bottom of the cycle! The management doesn't want a handful of savvy shoppers to clean the store out of its super duper supermarket deal. They want to share the wealth with as many customers as possible to build loyalty.

Sell-by Dates Have a Pad. Know the difference between a "sell by" date and a "use by date." For example, meat on sale is a good deal. Sale meat on clearance because it's close to the "sell by" date is a great deal. It's perfectly safe. There's a time cushion with a "sell by" date because it's not a "use by" date. Then, when you freeze that meat, you are also freezing it in time.

Many stores have rain check policies. If you find that an item is sold out because the store is offering a deep discount, ask for a raincheck. Often it's a formal rain check policy, where you actually get a little receipt that shows you are entitled to the sale price when the item is restocked. Ask for this paper proof if it's a product you really want to stockpile.

Products often go on sale in intervals. You can learn to see sales coming. If you keep track of the items on your top 20 list, you'll begin to notice that they are discounted like clockwork. The intervals vary depending on the product, but often popular items go on sale every 6, 8, 10 or 12 weeks. That's the time to stock up with enough to last you until the next cyclical sale!

Take advantage of Scanner Errors. Scanner errors are especially common on sale items. Grocery stores contain an average of about 47,000 different products, according to the Food Marketing Institute. It's easy for employees to miss some when they're programming new sales into the register. Studies have shown scanner errors are 3 to 1 in favor of the store --overcharging instead of undercharging. And that is actually good news because many stores have apolicy that if an item rings up wrong, you get it for free. Be vigilant and scoop up the freebies!

Bigger Is Not Always Cheaper. People assume you get a better price if you buy chicken broth in humongous cans instead of little ones. Or chips in big bags instead of snack size. Or diapers by the hundreds instead of by the dozens. But I have done several stories over the years where we showed that these very products are sometimes less expensive in smaller packages. It pays to pay attention to unit pricing to avoid this trap.