If the aim is to reduce cost, is it wise to split the drone and the camera ? In a comment to this one, the DIY drone is around 250$, the GoPro itself is 200$, the Bebop drone (whose camera actually use the same sensor than a GoPro) includes drone and camera (allowing to use flight information to improve video, and video to improve flight control), cost does not seem to be the right reason to make DIY drone. Technical interest may be relevant, as well as specific requirements, but cost is rarely a benefit from DIY.
My comment isn't neutral, as I work at Parrot, but I think it is honest. I also make my comparison with an expected price of 500$ for the Bebop drone, but I have truly no idea of what the actual price will be.