A woman walks past a dollar discount store in Brooklyn, N.Y. Ninety-nine cent stores, also called dollar stores, have been growing in popularity throughout the U.S. (Spencer Platt/Getty Images)

Dollar stores once had a reputation for selling low-quality products on the cheap. Sure, you could buy paper towels there, but would you buy something edible? Isn’t everything expired?

“People have the perception that you’re buying weird, off-brand or expired goods, but dollar stores have reinvented themselves,” says Jody Rohlena, senior editor of ShopSmart magazine. “In this economy, everyone is looking to save money. Three out of four women polled said they’ve shopped in a dollar store at least once this year. You can find very good prices.”

And chain dollar stores, such as Dollar General and Dollar Tree, are expanding across the country to meet the demand. These stores offer a wide array of merchandise for low prices (often more than a buck though) on everything from groceries to personal-care items. But what should you buy? What should you avoid? Here are some tips for shopping the reinvented dollar store.

Tips on what to buy, what to avoid

It’s not just a dollar

The name might be deceiving. While some outlets do only sell dollar products, the larger chain stores sell a wide variety of items on discount. Much of the time, you’re going to pay more than a dollar for products, but the variety of prices means you’ll get a wider array of goods.

Buy dollar-store brands

ShopSmart recommends checking out a store’s branded items. “We found savings of over 37 percent on items like quick oats and cereal.” Sure you may not be getting Quaker, but you’re getting a similar product for much less. ShopSmart also found that their secret shoppers saved 26 percent on pantry items such as flour. “We have tested a lot of private-label brands from the dollar stores, and some are as good or better than national brands.”

Take your grocery list

Rohlena advises shoppers to check out the food items at dollar stores, as many of the stores have become substitutes for major grocery chains. “You’re going to see freezer cases, condiments, packaged foods, soups and spices,” she says. “And they’re offering a lot more everyday items than what you find at the grocery store.” On packaged foods and single packs, prices are often much better at dollar stores.

Check expiration dates

While many stores are buying first-run items and national brands, always check expiration dates, whether you’re shopping in a big-box store or a discount retailer. “I would say that you want to be careful when buying electronics, vitamins or any electrical products,” Rohlena says. “You always want to check expiration dates on medications and food.”

Visit the Web sites

Dollar stores are known for being catch-all shops, but it turns out they’ve moved online: “One surprise is that you can order some things offline,” Rohlena says. “While you may have to order these items in bulk, it’s useful if there’s something you go through quickly, like a snack your child loves.” Also, these Web sites contain up-to-date information on product recalls and safety information, so if you’re unsure about a product, visit the Web site. They’re tracking that information for you.

Fill-in shopping

Dollar stores are looking to become midweek fill-in shops for people who want to navigate a store quickly.“They’re great if you need to pick up random things from cereal to garbage bags to a notebook for your child,” Rohlena says. Since they tend to be smaller than big-box stores, you can run in and out quickly. But know that in terms of the merchandise, dollar stores tend to sell seasonal goods. And there’s no guarantee that the product you bought last week will be there next week. Their inventory changes all the time, so it pays to visit often.

Buy personal care

When it comes to products and personal care items such as cosmetics, hair-care products and hygienic products, you can find a lot of national brands in dollar stores. In fact, Rohlena says, these are some of the most popular products. “As long as packages are not open, there’s no reason to be leery of them.”

Buy for the party

When ShopSmart asked readers what they like to buy at dollar stores, party supplies were among the most frequently given answers. Dollar stores sell tissue paper, cards and gift bags on the cheap. It’s always good to stock up.

Avoid party favors and toys

There are items you should avoid. Dollar stores do sell kids toys and party favors, and some of those items are choking hazards for kids. “Use the toilet paper tube test: If the toy fits in the tube, you shouldn’t buy it,” Rohlena advises. Also, avoid some of those inexpensive party favors they sell near the gift bags. Those, too, can be health hazards.