Fair play to this guy. That concept looks fantastic and well thought out. I'd want to have a fail safe for the 'clip in' personally cause temperatures and tolerances can cause 3D printed clips to be somewhat sketchy and no one wants their Hero falling from the skies if the board glitches out and shakes it loose.
If it proves successful to the people that buy it then I hope someone with a mass production setup can take it on and get the price down a bit.
My worry with anything like this is that the creator will, of course, have the best intentions in the world to share his creation and sell it to make a bit of cash. The issue though is the backlash that may come from a home designed/manfactured product like a Gimbal (with £350 hard earned camera lashed too it). Customer service is enough to consume a persons free time. Jay of Firebug OSD (FBOSD) was a prime example of this... from the back and fourths I had with him it was clear he was a really nice guy and desperatley wanted to make a mass production product for the masses but testing, customer problems and massive demand made it impossible to sustain the project.
Its also actually $440 for the Phantom version so with the likes of AeroXcraft, Tarot and Arris I think he's gonna have his work cut out. Still who knows this one might do ok and as a fellow designer I really hope it does.