eBay (Nasdaq: EBAY) wants to make a bigger splash in comparison shopping. The leading online marketplace is buying RedLaser, a popular barcode scanner application for smartphones.

RedLaser allows Apple (Nasdaq: AAPL) iPhone owners to scan any barcode they come across. The app then comes back with the lowest prices among online retailers and those carrying the product locally.

It's a hot program, and it's only going to get bigger. As of last month, RedLaser had been downloaded 2 million times, with nearly half of those remaining active users. More than 50 million barcodes have been scanned using the app. Now eBay has nixed the application's $1.99 price tag and made it free for all users. It's currently one of the Top 50 most downloaded free apps through Apple's virtual storefront.

There's naturally a reason for eBay's generosity. In its current incarnation, RedLaser relies on comparison-shopping sites, including TheFind.com and Google's (Nasdaq: GOOG) Product Search, to smoke out competitive prices. Under eBay's wing, RedLaser will be able to lean on its Shopping.com retail partners and even actual eBay listings.

eBay's namesake auction-site application and mobile PayPal program are already hits in the smartphone space, so RedLaser will be one more way to reach out to Web-savvy consumers who are affluent enough to afford high-end wireless devices.

eBay's in a unique position as a third-party marketplace with its own transaction platform, allowing it to make wider bets when it comes to comparison shopping than Amazon.com (Nasdaq: AMZN) and Overstock.com (Nasdaq: OSTK) -- standalone e-tailers with App Store shopping programs.

RedLaser is a perfect fit for eBay, leaving search engines and other comparison-shopping sites with no choice but to shop around to compete.

Have you ever tried a barcode scanner app? Share your experiences in the comments box below.

Google is a Motley Fool Rule Breakers choice. Apple, Amazon.com, and eBay are Motley Fool Stock Advisor recommendations. Motley Fool Options has recommended a bull call spread position on eBay. Try any of our Foolish newsletter services free for 30 days.

Longtime Fool contributor Rick Munarriz is a satisfied eBay user with 177 positive feedbacks to show for it. He owns no shares in any of the companies in this story and is also a member of the Rule Breakers analytical team, seeking out the next great growth stock early in its defiance. The Fool has a disclosure policy.