The Eachine H8 Mini is probably the Word’s cheapest quadcopter. You can read my review here: http://www.firstquadcopter.com/quadcopter-reviews/eachine-h8-mini-quadcopter-review/
Eachine H8 Mini features:
RTH and Headless mode;
Dual speed mode;
Up to 7 minutes of flight time;
control range around: 20 meters;
Suitable for indoor and outdoor flights.