Did you recently upgrade to the latest HTC or Samsung smartphone and want to dump the old one? While sites such as eBay and Craigslist are well-known reseller options, an alternative is GameStop. The video-game retailer, which operates 65 stores in Colorado, in April expanded its trade-in program to include a variety of smartphones. Customers can now receive instant cash or in-store credit for mobile phone trade-ins. For example, the retailer is offering up to $230 for a Samsung Galaxy S3. Check the trade-in value of your device at gamestop.com/devicetrader. Andy Vuong, The Denver Post