Comparison shopping is easy when you're sitting in front of your computer, but how can you be sure you're getting a good deal when you're at a store. Below we've taken a look at three cellphone-based services that claim to save you money when you're on the go. But can these services really rack up earnings or will they flood your mobile with useless text messages? Amazon TextBuyIt Last Wednesday, Amazon.com launched TextBuyIt, a free service that lets you shop Amazon's site via SMS. Shoppers simply text the name or UPC code of the item they want to buy to "AMAZON" (262922) and Amazon will text you back with potential matches. You then reply with the number of the item you want to buy and Amazon will call you to confirm the order. The service is very straightforward and works with little to no lag. We searched for Griffin's Evolve iPod Speakers by texting "Griffin Evolve" to Amazon and within seconds received the first of two text Amazon texts. The first text message explained the commands for using the service. For instance, texting "1" buys the first item whereas texting "2" buys the second item (only 2 potential matches are sent per text). For more information on an item, you type "1d" or "2d" respectively. Likewise, typing "m" or "h" provides you with more potential matches and a help menu. We texted "1d" to get more details on the first match and immediately received a text with the Evolve's Amazon rating and a URL that brings you to Amazon's webpage for the Evolve. Item 2, however, was not the Evolve, but instead the Griffin Amplifi. Next we searched for the Creative GigaWorks T40s. Again, Amazon successfully matched our search within the first try. (We eventually managed to stump it by texting "Rio Karma", a now discontinued MP3 player.) Next we tried searching for a music CD, Gotan Project's La Revancha del Tango. A few seconds after opting to buy it, we received an automated phone call from Amazon asking us for our e-mail and zip code to confirm the purchase. You can still cancel the order at this point, in which case Amazon texts you again notifying you of the canceled order. A few things worth noting. Amazon has good prices on many items, but it doesn't have the lowest price on most items it sells. So, if you really want a deal on an item at a big box store, this service won't solve your problem. You must also remember to factor in shipping charges, which Amazon leaves out of its text messages. Additionally, when using the service, make your searches as detailed as possible. For instance, instead of typing "Apple iPod," type "Apple iPod 4GB Nano." And finally, expect to send and receive up to 5 texts per item inquiry, so if you don't have unlimited text messaging, the cost of the messages may wipe away any savings. Cellfire Cellfire is a free mobile application that downloads and stores digital coupons on your Web-enabled cellphone. Shoppers can then summon the coupons from their mobile and use it at participating stores. (The checkout person types the code into the register.) The coupons vary by ZIP code and range from free movie rentals to food discounts. In theory, the idea sounds great for bargain hunters. However, our main fault with the service is its lack of participants. We tried it with ZIP codes 11201, 35806, 60601, and 33128 and yielded nearly identical results each time. Moreover, there are practically no clothing or electronics stores represented. And like Amazon's TextBuyIt, you're responsible for data charges to your phone. Frucall Powered by Amazon.com, Shopping.com, Yahoo! Shopping, and StreetPrices.com, Frucall is a free service that lets you comparison shop via your cell phone using these sites as search engines. The service is similar to Amazon's TextBuyIt, but with more features. For example, Frucall can be accessed via text message (by texting FRU11 or 37811), via phone by calling 888-DO-FRUCALL, or via the Web. We searched for the Creative GigaWorks T40s again and this time found a better price via Frucall ($115) than we did via Amazon's TextBuyIt ($134). We also like that Frucall lets you bookmark searches, create wish lists, and can even be set to call you when there's a 3%, 5%, or 10% price difference from the price Frucall texts you and the final price you must pay, which includes shipping and tax. Our favorite Frucall feature, however, is its price alert system, which notifies you via e-mail, text, or both when a product you want hits a price low, which you specify in your Frucall profile online. However, as much as we liked Frucall, the "lowest price" it claims is based on its network of affiliate stores. PriceGrabber, for instance, isn't checked when doing price comparisons. In addition, the service tends to have good coverage of electronics but bad coverage of soft goods, like food and designer clothes. Amazon vs Frucall Side-by-Side Comparison Amazon TextBuyIt Frucall Lowest Price Online* Griffin Evolve iPod Speakers $265.72 $231.76 $235.41 Creative GigaWorks T40 $134.78 $115.87 $106.33 Gotan Project (Music CD) $13.99 $12.45 $12.45 How I Met Your Mother Season 2 DVD Set $29.99 $27.21 $19.99 *Price determined via PriceGrabber.com, Shopping.com, and Google Product Search. Louis Ramirez is a dealnews Features editor.