Many online shoppers are being charged prices based on their personal data through a tactic companies call "personalized pricing," according to author Lindsay Owens.

"What we're seeing is Big Tech sort of reinventing the rip-off," said Owens, author of Gouged: The End of a Fair Price — And What That Means for Your Wallet. The book, published in September, uncovers pricing schemes that corporations try to hide and shares advice on how to protect yourself from these tactics.

Under personalized pricing, two people buying the exact same microwave or sweater may pay different amounts because of who they are, where they are and their purchase history, Owens said.

Owens offered several tips to make it harder for retailers to gather personal data and use it in pricing decisions. She said shoppers should avoid shopping through retailer apps, because signing in gives companies information including your location and purchase history. They even "know what you click on and don't buy," she said, and that data can "potentially be turned against you in pricing decisions, whether that's fewer discounts or higher prices."

She also recommended clearing browsing data and cookies regularly. "If you can clear that data before you make a purchase, then that data isn't available to the company to use against you," Owens said.

Other steps include limiting the permissions granted to apps, such as location access and inter-app data sharing, and considering a virtual private network, or VPN, which hides your location. Owens said shoppers can even run their own pricing experiments by using a VPN to change their location and "see if you can get a more competitive price coming from a different space," such as the San Francisco Bay Area versus Nashville, Tenn.

Owens said comparison shopping now also means ensuring "you're not being exposed to personalized pricing." She suggested checking a product's price across multiple devices, with and without incognito mode, and asking friends to check prices on their devices to confirm you are getting a fair price.