Galaxy S5 Developer Edition (model number ET-G900VMKAVZW) has been released by Samsung. The device is available exclusively on Verizon. difference between the developer edition smartphone and the Galaxy S5 which you can buy from Verizon is that the former comes with an unlocked bootloader to giving you the freedom all Android phones should include out of the box. Verizon give you facilitating flashing custom ROMs on the device.
The phone is exactly the same as the model sold directly through Verizon stores in terms of specs, the only difference is again, that unlockable bootloader.
Galaxy S5 Developer Edition will only available in 16GB configuration in Charcoal Black and sold for $599 without contract. You can buy this device from Samsung Online Store by going here http://www.samsung.com/us/mobile/cell-phones/ET-G900VMKAVZW