Imagine that the price sticker on a store shelf could automatically change based on the price at another store, or who is walking by. That's essentially what happens online: Retailers continually change their prices in response to market conditions -- and may use shoppers' personal information to charge different people different prices. ZIP codes, search histories, and other factors inform this so-called variable pricing or "price discrimination," according to researchers from Northeastern University. Sometimes it means a better deal, but in other cases the price is higher. While there's no foolproof method to guarantee the lowest prices, shoppers can experiment with a number of strategies that might stack the deck in their favor.
Try different browsers.
Search for a product using as many web browsers as possible (Chrome, Firefox, Internet Explorer, Safari). How-To Geek shows how to change a browser's "user agent" to fool sites into thinking they're being visited by different browsers (and different versions of those browsers), a quick way of testing prices without downloading additional software.
Go incognito.
Websites use software called "cookies" to track and monitor what people do online. The data they gather is sometimes used to determine the prices shoppers see. But browsing in "incognito" or "private" mode deprives them of this information and compels them to show the default prices. Clearing a browser's cache and cookies in normal mode can have a similar effect.
Use a different device.
If shopping from a desktop computer, try searching on a smartphone or tablet, and vice versa. With so much business now taking place on mobile platforms, retailers are taking notice -- and their mobile apps may display different prices than their websites.
Be a PC.
If possible, shop on a Windows computer instead of a Mac. Research has shown that Mac users tend to have higher incomes and spend more online, which has prompted some companies to charge them higher prices or "steer" them toward higher-priced options in search results. A Wall Street Journal test in 2012 found that Orbitz displayed higher-priced hotels more prominently to Mac users than to PC users, burying the lower-priced options deeper on the page.
Relocate.
Have a friend in a different ZIP code try doing the same search, and compare results. People in wealthier areas are sometimes charged more. A virtual private network or proxy server can be used to change a computer's IP address to fake a connection to the Internet from a low-income area or a different city.
Sign up.
If a site offers membership, take it; members often get better deals. For instance, expect to find cheaper flights on United Airlines while logged in as a MileagePlus member than while searching as a non-member. Besides seeing cheaper prices, members often get coupons and other exclusive savings.
Cross-check deal sites.
Many sites aggregate low prices online, so consult them before buying to make sure you're seeing the same deals. Try looking up a desired item on sites such as Slickdeals, FatWallet, or Brad's Deals.
Use price trackers.
CamelCamelCamel tracks prices for Amazon items over time and alerts users to price drops. Looking at price graphs can reveal patterns -- whether an item sells for less on a particular day of the week, for instance. Pricepinx is a similar price-tracking service that can be used for other shopping sites in addition to Amazon.
Enlist Paribus.
This service helps shoppers get money back from retailers who are continually displaying different prices, in exchange for a 25 percent cut of the refund. If the price of an item decreases after purchase, or a coupon code is available, Paribus negotiates a refund on behalf of the shopper (many retailers offer price adjustments within a specified period). Users give Paribus access to their email to send refund requests on their behalf, so it's a good idea to have an email address exclusively for online shopping.