This Moto Mod turns your phone into a walkie-talkie - The Verge
Amazon.com: Walkie Talkie Phones Zello PTT Button APP WiFi Mobile Radio 3G/4G Network 100 Miles Long Range Smartphone GPS Android KSUN ZL30 : Electronics
Best Buy: Motorola Pay-As-You-Go Cell Phone with Walkie-Talkie (Boost Mobile) BOOST I450
Amazon.com: Retevis RB20 Walkie Talkie Phones,4G Network Walkie Talkies with 4000mAh Rechargeable,Long Range Walkie Talkies 1000 Miles with GPS Tracker(2 Pack) : Electronics
Runbo X5 and X3 rugged Android phones moonlight as walkie-talkies, cost just $320 | Engadget
DMR UHF 4G LTE Android Rugged Smartphone PTT Walkie Talkie POC Radio Cell Phone | eBay