Shoppers who dismiss rebate and refund offers as more trouble than they’re worth should think again. Each year, I receive about $2,500 in rebate checks for buying products — primarily in supermarkets — that I would have purchased anyway. I have gotten rebates for buying cereal, detergents, dog food and frozen pizza. Many of the rebates are $5 or more. That’s a very respectable return on the few minutes required to clip out a few proofs of purchase and complete a short rebate form, even after subtracting the cost of a stamp and an envelope.

Bonus: The IRS considers rebate checks a reduction in purchase price, not income, so this money is tax-free.

Locating great rebates

Rebates often are not widely publicized. To turn rebates into a steady stream of income, you need to know how to find them…

Look for altered product labels. Specially marked packages sometimes signal rebate offers. Before you put an item in your cart, scan the shelf to see if other boxes, other sizes or competing products feature unfamiliar wording or graphics. Also, keep an eye out for shelf displays featuring small peel-off pads of rebate forms.

Be particularly vigilant when shopping for items in categories with a lot of competition, such as cereal and coffee… household cleaners and detergents… beer… and paper goods. Rebates are particularly common in these categories. These also tend to be products that don’t go bad quickly, if at all, making it safe to stock up if multiple items must be purchased to earn the rebate.

Example: Receive a $10 rebate by purchasing $20 worth of 3M Permanent labels or Post-it Notes by the end of 2010 (www.3MProductivity.com, then click “Special Offers”).

Sign up for the e-letters of companies that make the products you buy. These newsletters often feature rebate offers as well as other savings. Find a company’s Web site by typing its name into Google.com, then look for a link on the site labeled “Sign up” or “Special offers.”

Recommended: Create a special e-mail account to use for these newsletters so that your main e-mail account is not flooded with product offers and updates.

Skim newspaper and magazine ads for rebate offers. Sunday sales circulars usually are prime sources.

Sign up for pharmaceutical chain rebate programs. CVS (www.CVS.com), Rite-Aid (www.RiteAid.com) and Walgreens (www.Walgreens.com) run extensive rebate programs on many kinds of products, including over-the-counter medications, baby food and household cleaners. These programs are now Internet-based, so you don’t even have to mail in rebate forms.

Examine the packaging of any product marked “new” or “new and improved.” New and updated products are particularly likely to feature rebates because companies know that they must provide special inducements to convince consumers to try something different.

Example: Specially marked packages of Kellogg’s new cereals Cinnabon and Corn Flakes Simply Cinnamon offer a rebate for the full purchase price paid — you can try the cereals for free.

Click the “Rebate Center” link on the Web sites of office-supply retailers, such as Staples (www.Staples.com) and Office Depot (www.OfficeDepot.com). These typically feature a wide range of rebates on everything from paper to computers.

Example: Get a $50 Visa prepaid card when you recycle any printer and buy a Lexmark Laser Printer priced at $199 or more.

Ritz Camera’s Web site is another good place to find valuable discounts on consumer electronics (www.RitzCamera.com, then click “Rebates & Coupons”).

When you shop at Bed, Bath & Beyond, stop by the customer service department and request the sheet of current manufacturers’ rebate offers.

Examples: Recent Bed, Bath & Beyond rebates include $10 off an Oneida 18-inch nonstick roaster pan and $10 off Cuisinart coffeemakers.

Rebates can be used in conjunction with the widely distributed Bed, Bath & Beyond coupons, which often provide 20% off any single item or $5 off purchases greater than $15. If you don’t get these coupons already, sign up to receive them at www.BedBathAndBeyond.com (click on “Email Signup”).

Before buying oil, antifreeze, air filters and other automotive items that require frequent replacement, check product packaging and shelf displays for rebate offers. The companies that make these products know that people who work on their own cars tend to be very brand loyal and that a big rebate might be the only way to lure them away from the competition.

Example: Receive a $5 to $7 rebate when you buy a gallon of Prestone Antifreeze by the end of January (www.Prestone.com, then select “Special Offers Available”).

Visit the refund discussion board at my Web site, CouponQueen.com. Select “Blog,” followed by “Discussions,” then “Manufacturers Refunds” to read about recent rebate offers.

Getting the most from rebate offers

Strategies to maximize rebates…

Create a label supply network. Tell your friends and relatives that you’re collecting proofs of purchase and receipts from particular products, or post this on your Facebook page. People who don’t bother with rebates might be happy to hand over their labels. Those who do use rebates might be willing to swap with you if you are pursuing different offers.

Save promising labels and receipts even if there is no rebate. Some companies — such as below — offer rebates so frequently that it’s worth saving proofs of purchase even when a rebate isn’t offered. You might be able to use them if a new rebate offer appears soon. Save your grocery store register receipts, too — many rebates require these. Helpful: I save proofs of purchase in shoe boxes… refund forms in an envelope… and receipts in another envelope.

Seek out free samples. Receiving a free sample in the mail might not be quite as appealing as receiving a rebate check, but samples have one big advantage over cash-back rebates — you don’t have to purchase anything to earn them. You might not even have to use a stamp — many free samples now can be obtained by completing a quick online form.

Example: The Web site www.AllYou.com offers a new free sample each day. Click the listing in the “Daily Free Sample” box. You also can request the freebies offered on previous days by clicking “See full calendar,” then choosing earlier dates.

Top 10 Companies for Supermarket Rebates Now

The following companies offer rebates much more often than most…

Colgate-Palmolive. www.Colgate.com

General Mills. Brands include Betty Crocker, Bisquick and Pillsbury. www.GeneralMills.com

Kellogg’s. www.Kelloggs.com. Example: Submit five tokens from specially marked packages of Special K cereal by year-end to get a voucher for $10 off a new pair of jeans.

Kraft Foods. Brands include Maxwell House, Miracle Whip, Oreo, Oscar Mayer, Planters and Ritz. www.KraftFoodsCompany.com

Nestlé. Brands include Carnation, DiGiorno, Dreyer’s, Häagen-Dazs, Hot Pockets, Stouffer’s and more. www.NestleUSA.com

Nabisco. www.NabiscoWorld.com. Example: Join Nabisco’s Facebook page, and qualify for discounts on Nabisco cookies each month.

Ragú. www.Ragu.com

S.C. Johnson. Brands include Drano, Glade, Off, Pledge, Raid, Shout, Windex and Ziploc. www.RightAtHome.com. Example: Free Ziploc freezer starter kits recently were offered.

3M. Rebates on Scotch Tape, Post-it Notes and other home and office products are common. www.3m.com