You no longer have to buy online to give the Amazon Echo a shot. Amazon will soon sell the smart, voice-guided speaker in more than 3,000 retail stores, including Brookstone, Fry's, Home Depot, PC Richard & Son, RadioShack, Sears and Staples (which previously sold it on the web). The rollout is taking place over the next few weeks, and a few big stores are conspicuously absent in the mix -- Best Buy, anyone? Still, this beats worrying about holiday shipping headaches.