If you’ve ever left an item in an Amazon shopping cart for a few days, you may have seen an alert when you returned to your cart showing a price drop—or increase. That’s dynamic pricing at work. Many online retailers shift their prices as they monitor competitors’ pricing and customer demand. Some even use what they know about your shopping habits and location to set the prices they show you.

“This way of doing business isn’t typically illegal,” says Norman Silber, a consumer law professor at Hofstra University in Hempstead, N.Y., and a former CR board member. The exception, he says, is pricing intended to stifle competition or that considers prohibited factors like gender or race.

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Dynamic pricing lets retailers exploit differences among consumers, notes Z. John Zhang, a professor of marketing at the University of Pennsylvania’s Wharton School. “It’s almost a game that retailers play,” he says.

But it’s a game you can play, too.

Let items sit in your shopping cart. If you’re not in a rush, log in and put that digital camera into your shopping cart. Revisit the cart a few days later. You may see a lower price. Be aware, though, that prices may also rise.

Use a different ZIP code. A Wall Street Journal report found that some online retailers charge differently based on ZIP codes. Home Depot, one of the retailers studied, told us it sets its online pricing based on the price at the walk-in store closest to the consumer. (Stores prices can differ by location.) Input a friend’s or relative’s ZIP code, or enlist someone in another ZIP code to shop for you. Make sure any extra shipping cost and inconvenience don’t undermine what you save.

Use price alerts. You can set up notifi­cations about Amazon price changes using such websites as camelcamelcamel.com and joinhoney.com. Travel websites such as Expedia, Kayak, and Travelocity offer alerts for price changes on specific itineraries or hotel stays.

Shop for holiday airfares with and without your cookies enabled. On sites such as Hotwire, Kayak, and Google Flights, search multiple times over several days, both with and without clearing your history or “cookies,” the data files that record previous web searches. (Go to the “history” or “privacy” section of your browser and look for “clear cache,” “clear cookies,” or “clear browsing data.”) When CR testers tried this for identical flights on nine different sites in 2016, the prices they got differed by as much as $238.

Black Friday vs. Cyber Monday: When Do You Get a Better Deal?

The answer: It depends on what you’re buying. We chose four high-on-the-wish-list holiday gifts—televisions, laptop computers, fitness trackers, and smartwatches—and looked to see which of the two promotional sale days offered the best deals in 2016. Consumer Reports partnered with Gap Intelligence, a market research company that specializes in retail pricing data, to analyze price fluctuations during the 2016 holiday period. The prices were averages for all models within each product category.

Though laptops were cheaper last year on Black Friday (the day after Thanksgiving), the other products were priced lowest on Cyber Monday (the Monday after Thanksgiving). Sometimes the price differences were puny. Compared with the rest of the year, though, the savings were more significant. Also worth knowing: Prices were comparable when we compared 2016 online vs. in-store prices on those sale days and year-round.—Nikhil Hutheesing

TVs

BEST TIME TO BUY: Cyber Monday

The average price on Cyber Monday was $329 lower than the peak price in 2016 and $45 lower than for Black Friday.

Laptops

BEST TIME TO BUY: Black Friday

The average price on Black Friday was $35 lower than the peak price in 2016 and $8 lower than for Cyber Monday.

Fitness Trackers

BEST TIME TO BUY: Cyber Monday

The average price on Cyber Monday was $31 lower than the peak price in 2016 and $11 lower than for Black Friday.

Smartwatches

BEST TIME TO BUY: Cyber Monday

The average price on Cyber Monday was $29 lower than the peak price in 2016 and $6 lower than for Black Friday.

TVs

BEST TIME TO BUY: Cyber Monday

The average price on Cyber Monday was $329 lower than the peak price in 2016 and $45 lower than on Black Friday.

Laptops

BEST TIME TO BUY: Black Friday

The average price on Black Friday was $35 lower than the peak price in 2016 and $8 lower than for Cyber Monday.

Fitness Trackers

BEST TIME TO BUY: Cyber Monday

The average price on Cyber Monday was $31 lower than the peak price in 2016 and $11 lower than for Black Friday.

Smartwatches

BEST TIME TO BUY: Cyber Monday

The average price on Cyber Monday was $29 lower than the peak price in 2016 and $6 lower than for Black Friday.


Visit 
Consumer Reports' 2017 Holiday Gift Guide for updates on deals, expert product reviews, insider tips on shopping, and much more. And be sure to check our Daily Gift Guide.
 

Editor's Note: This article also appeared in the December 2017 issue of Consumer Reports magazine.