Amid buzz about Apple's new iPhone 6, Sprint is unveiling a new plan that allows customers to get a new iPhone every two years -- for life. As part of Sprint's new 'iPhone for Life Plan,' customers can receive the new iPhone with no upfront cost. Instead, they'll pay $20 a month to rent the phone and $50 a month for Sprint's unlimited plan, resulting in a total commitment of $70 a month. Sprint says that's its lowest monthly cost for both phone and plan, saving customers $575 over its two-year agreement. The plan applies to new and existing customers, who can pay the same price to rent the iPhone 6 or the iPhone 6 Plus.