I notice recently that some of the cheaper toy quads, they are using optical flow camera with the height hold. Thought I would give this little $15 sucker a try out. Very impressed how it holds itself at hover with no GPS, even with Fans, air conditioning going all around it. Been wanting a inside camera mini drone that does not drift around and this one does not and for just $15. Amazed how cheap the quad tech is getting. It also comes in black color.
Product Info: https://www.amazon.com/Quadcopter-Optical-Altitude-Headless-Movement/dp/B071WM3NPN/ref=sr_1_1?ie=UTF8&qid=1523339179&sr=8-1&keywords=beebeerun+optical