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Shopping online deals? You can do better

Black Friday doorbusters aside, shoppers are planning to pick up more holiday bargains online this year—or at least, they'll try. Success is far from guaranteed.

Online sales could grow by as much as 11 percent this year, according to the National Retail Federation. Over Thanksgiving weekend, 54 percent of shoppers say they will go online, versus 45 percent in-store, reports Deloitte. (Even on Black Friday itself, the percentage of people who said they planned to shop online48 percentwas about equal to those who said they'll go to the mall.)

But online prices can be a moving target. A recent Northeastern University study found that more than half of the 16 big retail and travel sites assessed showed different price results for the same search, depending on who was conducting the search and on what kind of device.

"This [can be] good for users who are aware of deals and use them," said study co-author Christo Wilson, an assistant professor at Northeastern. "Everybody likes coupons. But that said, not everyone knows about the deals."

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Every retailer has its own strategy for personalizing deals, so gut-checking a price requires a varied approach. Use the cost of the item as a gauge for how much work to put in. "The effort should be toward items that are a significant dollar amount," said Jack Vonder Heide, president of Technology Briefing Centers.

Start with the tried and true: a price comparison search using an engine like PriceGrabber.com or NexTag.com. Don't forget to factor in shipping fees, too, which can make a big difference in the final price, said Matthew Ong, senior retail analyst at NerdWallet.com.

Once you've picked a likely contender, check that retailer's price for differentiation. Try a different browser, and experiment with the private browsing features on each, Wilson said. Logging into your account with that retailer, instead of checking out as a guest, can also make a difference. If you're shopping on a laptop, check to see what price your tablet or smartphone pulls up.

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You could go so far as to clear your Web browsing history of "cookies" that track your searches and retailer visits, said Vonder Heide. But it's a risky move: Some sites' algorithms push lower prices to users whose history shows repeat business or significant price comparisons. If that's the case, scrubbing your history will erase that deal, too. "You really don't know the peculiarities of any particular website until it's too late," he said.

Another extreme strategy? Call a friend or family member in a different area of the country and have them look up that TV, computer or other expensive item online. "Sometimes they will find a much better price," said Vonder Heide. If that's the case, that friend can check out for you, using your credit card number and address.

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Before you check out, look for stacking opportunities. Linking to the retailer through a cash-back site like FatWallet.com or a loyalty program mall nets extra points. "Of course, always check for coupon codes right before you check out," said Ong. "It's one of the easiest things to do, and there's no reason not to do it." (Google "promo code" or "coupon code" and the retailer.)

Even after a purchase, you may be able to secure savings. Credit card issuers including MasterCard, Discover and Citibank offer price matching programs if you spot a better deal after the fact. Check the program details and set up a price-drop alert on sites like TrackIf.com and Cartbound.com so you can file a claim.