Not so fast.

Step away from the "purchase" button. According to an investigation from The Wall Street Journal, shopping sites run by companies like Staples, Discover Financial Services, Rosetta Stone and Home Depot show customers different prices and deals based on what they know about you, including geolocation. 

The paper reports that Staples.com showed higher prices 86 percent of the time "when the ZIP Code actually had a brick-and-mortar Staples store in it, but was also far from a competitor's store." However, New York City was an exception:

"Tests of Staples.com using ZIP Codes in the boroughs of the Bronx, Manhattan and Staten Island consistently saw higher prices, while Brooklyn and Queens saw almost only the discounted prices. This despite the fact that all parts of New York City look to be within 20 miles of a Staples competitor, according to the websites."

Thank you, Journal, for giving us an excellent excuse as to why we didn't buy anyone Christmas presents this year.