An Amazon Prime membership will cost you $99 a year, but Sprint is tacking on the two-day shipping subscription for free. Starting today, the carrier is giving new and existing customers who choose its Better Choice XXL plan 12-month access to Prime. The XXL option is $100 a month on its own, giving users 40GB of data and unlimited talk and text. Sprint was already offering customers Prime access for $11 a month, but now it's offering folks who burn through data the chance to nab it at no additional cost.