Geeksphone, the smartphone OEM startup based out of Madrid, put the first Firefox OS developer phones on sale early Tuesday morning, offering the Keon for $119 and the more powerful Peak for $194. Both devices are the first hardware to be offered with Firefox OS on board, and both devices are now listed as “Out of stock,” just a few hours after first going on sale. The Keon and Peak devices are essentially preview devices, designed to give developers the opportunity to test out what they can do with the new Linux-based open-source mobile operating system before it sees its general public launch this June in five initial countries, including Spain, Brazil, Portugal and Venezuela. The Geeksphone devices are modest in terms of their hardware specifications, but Firefox OS will likely be positioned as more of a mid-market play.