By Jeff Bertolucci, Contributing Writer December 10, 2010 In the arena of haggling, knowledge is power. And the right application can put that power at your fingertips. Specifically, free price-matching apps are available for the Apple iPhone and dozens of mobile phones that run Google's Android software. How do they work? Rather than combing through ads, you check the phone to see which nearby store has the best offer. If you're already at a store and find a better price elsewhere, simply ask the retailer if it will match or beat the competitor's price. To try phone haggling, I used a T-Mobile G2 ($200 with a two-year contract) and two free apps available in Google's Android Market, an online store with more than 100,000 software programs accessible via the G2's main screen. Because of their power, simplicity and ease of use, my favorite shopping tools are Google Shopper and ShopSavvy, although there are many more. All price-matching apps work pretty much the same way. The easiest is to use your phone's camera as a bar-code scanner. For instance, using Google Shopper, select "Image Search" on the app's home screen, and then aim the camera at the bar code. Once it recognizes the code, the app beeps. Within seconds, Google Shopper displays all local and online stores that sell the product, the price they're asking, the stores' addresses, and their distance in miles from your current location. Advertisement But what if you can't find the bar code? Try a voice-recognition search -- say, for example, "Samsung 50-inch 3D plasma HDTV" -- or go old school and type in the product's name. A voice search may seem inherently unreliable, but it worked well in my tests of Google Shopper in Best Buy's noisy electronics department. ShopSavvy has a bar-code scanner and text search, but no voice option. Putting the apps to the test. At Best Buy I spotted a 32-inch Sony LCD TV for $400. Google Shopper found the same model at a Sears 27 miles away for $356. Too far. But at Staples, ShopSavvy discovered that a $210 APC Backup Battery, handy for surge protection and power outages, was $150 at Office Depot and $180 at Best Buy. And both stores were less than a mile away. Cha-ching. The app showed me that a short drive would save me 60 bucks. But would I have to make the schlep? I asked clerks at both stores whether they'd match the price I'd found with my phone. In both instances, they said they'd need to see a print ad to give me the better deal. (So last century.) Undaunted, I went to another Best Buy and scanned a Panasonic cordless phone kit with four handsets. Best Buy wanted $100, but a Wal-Mart nine miles away had it for $89. Would Best Buy match Wal-Mart's price? Yes. All I had to do was bring the Panasonic box to customer service, which would call Wal-Mart to verify the lower price. Next I ventured into Fry's Electronics, a big-box retailer with stores in nine states, where ShopSavvy informed me that a $499 Toshiba 32-inch LCD TV was $30 cheaper at a Best Buy a half-mile away. Fry's agreed to match the lower price after making the requisite confirmation call. I couldn't, however, get them to beat the competitor's price. Advertisement I called retailers to see whether they had a policy on shopping apps, and Best Buy said it does honor prices from them. Given my experiences, it's safe to say some clerks aren't aware of their store's policy, and it's incumbent on shoppers to seek out store managers and push the issue. Sometimes, shopping apps show that the price you see is the best in town. A Best Buy in my area, for instance, had a Currie Ezip 400 electric scooter on sale for $200; the next best price Google Shopper could find was $300. And Costco's $100 price for the iHome IP45BZ rechargeable stereo speaker (with FM radio and alarm, iPod and iPhone dock) was $3 less than I found elsewhere. No buyer's remorse here. If you suspect a certain item will go on sale soon -- after the holidays, say -- use ShopSavvy to create a price alert. Simply enter your target price and e-mail address, and the app will notify you when the price hits your target. Both ShopSavvy and Google Shopper keep a history of the products you've researched -- a handy feature for checking prices over time without having to reenter the same information again and again.