Sprint's initial iPhone 8 offer was fine, but nothing special: you could get half off the price of an 18-month device lease. It's ready to sweeten the pot, however. It just launched an updated promo that gives you a 64GB iPhone 8 for free with a trade-in and an 18-month lease. You still have to hand in a high-end device like one of the iPhone 7 models, a Galaxy S8 or a Galaxy Note 8, so this is more for frequent upgraders or those with a serious case of buyer's remorse. It's better than before, though, and you can apply the $29.17 monthly credit toward the 64GB iPhone 8 Plus if you crave a larger screen.