First off, looks like the "turn in your phone" deal for PagePlus is over, but remember that any Verizon, Alltel, Simple Freedom or Amp'd phone (and maybe any Sprint phone...I'll have to try that...) will work on the service.
Second, Amp'd is in deep trouble. Verizon is threatening to cut them off of their network. Why? Amp'd has declared Chapter 11 bankruptcy and owes a lot of people a lot of money, with Verizon being the biggest person they owe money to. So hold on, and if push comes to shove switch your phones over to Page Plus :)