AT&T is currently running a commercial touting its trade-in deal that will get you 50% off any smartphone up to $199.99. The company is also offering free activation for a limited time. It is a better deal, however to buy from AT&T directly online. If you act before the end of today, you don't have to pay the $36 activation fee. This is the one of the first times that we've seen prices directly online from AT&T beat online retailers such as Amazon, Wirefly and Lets Talk.
In order to get the 50% off in an AT&T store, you have to bring in a smartphone that is less than three-year's old. If you want 50% off the newest smartphones $199.99 and lower with a two-year contract, you don't have to trade-in any smartphone at all when you buy it from AT&T online directly. Of course you can trade or sell your smartphone on eBay if you prefer.