By Lindsay Sakraida, dealnews staff writer Keeping up with the fastest-selling items on sale from Internet retailers is like chasing your own tail. Just when you think you've caught up with it, it gets out of your reach because so many deals are just too good to last. On dealnews, we list around 300 deals per day, and, on average, 38 of them expire within six hours. If you're away from your computer during that indefinite window of opportunity, you just might miss out. While predicting the sell-out-ability of an item is an imprecise science, there are definite trends as to the types of deals that go the quickest. And now there's a solution to the problem: our new dealnews app launched last week, which means that anyone with an iOS-enabled device will have the entire dealnews site at his or her fingertips. So if your thrift-lovin' heart is tired of missing out on deals, be sure to set up Push Alerts through the app (or, via your mydealnews account online; you'll just need to select the mobile option after setting up the alert). That way you'll never miss any of our fast-paced deals, like these five hottest sellers: Amazon.com deals are twice as likely than those from any other vendor to expire within six hours. Likewise, the grocery category features the highest number of deals to expire within the same timeframe. Considering the vast majority of our grocery deals are from Amazon.com, a savvy reader would set up an alert with the parameters: Amazon, groceries, and the key words "Subscribe & Save". That said, prices and stock at Amazon.com in general can change quickly, especially when you factor in the store's daily Lightning Deals. Thus, any category that strikes your fancy is worth an alert at Amazon.com. A somewhat distant (but definitive) second place for "most expired vendor" goes to Meritline.com. This peddler of inexpensive accessories (and beyond!) releases several coupons each day that feature an extremely limited number of redemptions. So if you want to gobble up cheap adapters, cables, and more, it's important to act quickly. (Honorable mention: With its hot daily deals, combo bundles, and coupons, newegg.com is a close competitor for the title.) As a general rule, discounted Mac systems are a rarity and, ipso facto, a hot commodity. When you cross-pollinate that with an item of unknown or limited stock (e.g.: Apple-refurbished units), you're bound to get a fast-selling deal. Fans of Steve Jobs (and Justin Long) should therefore set up an alert for the key word "refurbished" and Apple. Nationwide store credits from daily deal sites like Groupon and its many emulators are often no-brainers if you ever plan on placing an order at the given store. (After all, a $50 credit for $25 is essentially 50% off.) However, with strict time and quantity limitations, these very obvious money-savers are sometimes maxed out in no-time. Get in on the savings by creating an alert for "credit" at Groupon, or the daily deal site of your choice. Men's apparel is another general category with a high number of quickly-expired deals. And even when an apparel deal lasts, often times specific sizes don't. Increase your chances of getting first dibs on the size and styles you need by setting up a few personalized apparel alerts. Track price drops on trendy buzz items You know how it goes: There's a hot new device that just got released, and you're itching to own it — ahem, iPad 2 — but your deal-driven conscious just won't let you pay retail. Instead, set up an alert; even if price drops are few and far between, our helpful little app will act like an alarm, alerting you to long-awaited savings on today's most desirable tech toys, like the Motorola Xoom WiFi Tablet, Nintendo 3DS, Android smartphones like the Motorola Atrix and HTC Thunderbolt, and anything Apple (iPod touch, MacBook Air, etc.). Or, if you're looking for a more general, yet similarly popular, tech category at a specific price point — like Core i7 notebooks under $800 or big-screen HDTVs around the $1,000-mark — set up a cost-driven alert via your mydealnews account and link it to the app. Filter and focus on the things you need You could set an infinite number of alerts for epic deals and universally hot items, but at the end of the day, the dealnews app is most useful for the things that are specifically important to you. For this reason, the app lets you create a completely customized feed that cherry-picks only the products and sales you crave. It's like building your own personal dealnews that's malleable to your daily whims. And while it may not feature the fastest-selling items, or the most blogworthy products, your feed has the things you want — and you can't afford to miss them.