ShopSavvy found another retailer is cheaper than Amazon. Source: Amazon.com.

This is shaping up to be the year all the rules of shopping were broken. First came the bombshell revelation from NerdWallet showing that Black Friday goods may not be quite the deals retailers claim, as many were selling year-old items at the same prices as last year's Black Friday. And if the newest report from ShopSavvy is correct, the decade-long maxim that Amazon.com (AMZN -1.35%) has the lowest prices could be wrong as well.

For those unaware of the company, ShopSavvy's purpose is to help would-be shoppers find the best deal on products by providing retailer information through its website and its barcode-scanning mobile app on Android and iOS. And if its recent ShopSavvy Showdown (say that three times fast) is correct, both Amazon and Best Buy (BBY -2.19%) offer higher prices on overlapping items than the undisputed King of Retail: Wal-Mart (WMT -0.35%).

The survey says ...
This survey is not the first showing that Amazon is losing its edge as the lowest-cost retailer. Earlier this year, a report from Wells Fargo and online price-tracking company 360pi found Amazon had higher prices overall when compared to Wal-Mart and Target in four critical areas: shoes, electronics, housewares, and health products. However, the report found that Amazon typically offered the lowest prices when it came to "like-to-like" items. Essentially, when a specific item was on both sites Amazon still had the lowest price.

However, this newest data finds the exact opposite. The survey, based only on the same products for sale at Walmart, Amazon, and Best Buy, finds that "Wal-Mart has the cheaper option on over 50% more products than Amazon and Best Buy across the categories analyzed." In addition, the survey notes Wal-Mart's online price match policy, in which the company specifically agrees to match prices from Amazon and Best Buy.

According to the ShopSavvy survey, Wal-Mart is the king of low prices. Source: The Motley Fool.

The survey results were rather shocking when compared with Amazon. In the heavily trafficked categories of electronics and TVs (the survey distinguishes between the two), Wal-Mart was cheaper on 66% and 85% of total products, respectively. The average percentage difference of price was 28% and 23%, again, respectively. Essentially, this survey finds that shopping at Wal-Mart, and not Amazon, for TVs and electronics will save you nearly a quarter of your money.

So I should go to Wal-Mart right now, right?
If these results are correct, you should go directly to Wal-Mart and not worry about shopping around online, right? Well, not so fast. As the survey clearly shows, Wal-Mart didn't always have the lowest price, although it was a good bet they did. In addition, the survey didn't go into a lot of detail about the product selection. Without that critical piece of information, it's hard to know whether these goods are representative of a true head-to-head comparison or whether these items are merely a good selection for Wal-Mart.

In addition, the data presentation concerns me. Although there were three retailers chosen for the survey, the data was only presented as Wal-Mart versus Amazon and Wal-Mart versus Best Buy. Without the third head-to-head comparison, Amazon versus Best Buy, the survey can come across as less of an unbiased comparison and more of a pro-Wal-Mart piece.

Finally, competition between megaretailers is rather intense. In many cases, retailers consider prices of 3%-5% lower as being worthy of running commercials specifically outlining these differences. The closest ShopSavvy comparison between Wal-Mart and the other retailers was in the TV category, with Wal-Mart being "only" 15% cheaper than Best Buy on average. When matched up against Amazon in the Kids category, ShopSavvy reports that Wal-Mart is a massive 45% cheaper on average.

Overall, this doesn't mean that ShopSavvy's data is wrong, but this should be considered only one data point in your holiday deal-hunting comparison. One shopping rule that will never be broken is to continue to shop around for the best deal; you'll be thankful you do.