ShopSavvy, Google Shopper and eBay's RedLaser are comparison-shopping apps that work in similar fashion but show prices charged for a particular item across the Internet and at other local stores.
If you're having trouble finding a store selling what you're looking for, apps such as Goodzer can help you source almost any consumer item, whether it's available at a chain store or local mom-and-pop shop.
The Consumer Reports Mobile Shopper allows you to instantly compare prices from both online merchants and local brick-and-mortar stores, plus it shows you the product reviews and insights the magazine is known for.
Shop around for a shopping app
The Consumer Reports app has an annual fee, $4.99 a year, while the others mentioned so far are all free. Often, you won't have to open your wallet for a great app that will save you money.
"When it comes to apps, the adage that you get what you pay for is really irrelevant as a litmus test for consumers to decide if they want to install an app," says Ryan Ruud, a digital media expert in Minneapolis who calls Target's free shopping app his "lifeline."
Ruud says plenty of great free smartphone shopping apps are available, often supported by advertising or provided by a particular store hoping you'll shop there. But understand that while a retailer's branded app may offer the latest deals and list-making features, it likely won't tell you if a competitor has a better price. So it's worth shopping around for the right app before you start doing the real shopping around.
To find a quality app, Ruud advises consumers to look at the reviews in an app store. If an app has several hundred reviews or more and the ratings are high, he says it's probably good. Likewise, regular updates for minor fixes are a good sign the app's maker offers ongoing support. If you pick the wrong app, you can always delete it and find another.
Shopping and talking?
Siri, Apple's voice-recognition tool, has been something of a sensation since it was introduced for iPhone last year. Now a number of popular shopping apps advertise the possibility of speaking to your smartphone instead of typing in a product or scanning a barcode to do a price check. Unfortunately, the more cutting-edge you are, the more bugs you're likely to encounter. Voice-controlled shopping apps -- available for both iPhone and Android platforms -- are still in their infancy, with kinks still to be worked out.
Craig Agranoff, a technology reporter and co-founder of Grip'd, a Boca Raton, Fla., company that develops iPhone and iPad apps, says he's not quite sure Siri is a useful mobile shopping tool just yet.
"Voice for product searching seems to be a bit far off for now since you're really hoping that the operating system recognizes what you said properly," says Agranoff. If the voice app doesn't understand you, you'll be back to manually entering product information or scanning the barcode.
But Agranoff points out that the speed of innovation in the mobile-app space is intense, so better voice recognition is coming.
Caution on privacy
While free apps can certainly help you simplify your shopping and save, they also raise some serious questions about consumer privacy, says Aaron Messing, a lawyer who specializes in information privacy issues at OlenderFeldman in Union, N.J.
"If you have a smartphone, it knows everything about you," he says. "Consumers should understand what types of data they will be sharing when they use a particular app."
Read the terms of service before installing any app. Messing says you also need to ask: Will this app have access to my location, pictures, contact book, and voice or text communications? If so, when will it collect that information, and how will the app use it?
Even people who are extremely cautious about their privacy may decide the benefits of smartphone shopping apps are worth giving up some personal information for, he says. All experts stress that whether a shopping app is free or costs you something, it will track your shopping habits because that's often how customized deals are targeted to specific consumers.