CONTROL SYSTEM OF QUADROTOR

For control system you will need to interface brushless controllers(ESC). so find some mixer that support such a high update rate (>200 steps/s). and see how it works.

also, find i way to interface with a rc-receiver,and the gyros, gyro sensitivity can vary from as low as 50 degrees/s to as high as 450 degrees/s we dont actually need very high sensitivity ,so no need to throw your money
once you have all that running, build a frame and buy the rest of the esc and motors. the actual stabilisation is (relatively) very easy.

i will be posting the interfacing diagram later