Personal Finance

Use these hacks to get the best online price for holiday gifts

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How sure are you that you're getting the best price for that online purchase? Better check.

So-called price differentiation means that different visitors to the same retailer could see varying prices on the same item. A 2014 study of 16 large retail and travel sites found that more than half showed different price results for the same search, depending on who was conducting the search, and on what kind of device.

"It's very hard to know why you're seeing what [price] you're seeing," said study co-author Christo Wilson, an assistant professor at Northeastern University.

Now, that same team of researchers, in conjunction with Volunteer Science, is aiming to raise the curtain on price differentiation. Their plugin for Chrome browsers runs the same search you did on the researchers' server, which doesn't have the same history or cookies as your machine, to show if other online shoppers are seeing a higher or lower price than you are.

If you're worried about differentiation at a particular retailer, try searching for that item using a different browser.

Better deals than you got pop up in red, Wilson said, while ones worse than you received show up in green. The plugin currently supports shoppers browsing Amazon, Google Flights and Priceline; more sites are in the works.

The plugin is free to use. Shoppers can elect to keep their searches private, or donate their search data from using it to help the researchers' price differentiation studies.

Every retailer has its own strategy for personalizing deals, so shoppers looking to gut-check a price should take a varied approach, said Jack Vonder Heide, president of consulting firm Technology Briefing Centers.

The easiest tactics are those you (hopefully) do routinely anyway: Use a price comparison search engine to see if there's a better price elsewhere, and conduct a separate search for coupon codes at the retailers where an item is the most competitively priced.

If you're worried about differentiation at a particular retailer, try searching for that item using a different browser, or a different device, said Vonder Heide. Shopping via your phone can often yield better prices.

"One of the methods they use for gauging what price they show that particular visitor is often the type of device they use," he said. "A lot of businesses are trying to target the mobile consumer, so they're offering incentives if you access the site on your mobile device."

If you're a frequent purchaser or a member of the retailer's loyalty program, try logging in before you shop. You may see better pricing or exclusive deals, he said.

Experiment with private browsing or incognito mode on your web browser, said Stan Black, chief security officer for software company Citrix. You might see different deals visiting with that clean slate.

You could also clear your web browser's cache of "cookies" tracking your searches and retailer visits. But that could be risky, Vonder Heide said: Some sites' algorithms reward loyal shoppers with better deals, or dangle a lower price to someone who recently comparison shopped with a competitor. Scrubbing your history could erase those deals, too.

After you buy, it's smart to set price alerts on those purchases. That way, if the price changes or you come across a better deal, you can try to snag a price adjustment.