DJI Official Store via eBay offers the factory-refurbished DJI Phantom 3 Professional 4K Quadcopter with 4K Camera, model no. CP.PT.000181 for $549.99 with free shipping. That's $19 below our refurb mention from two weeks ago and the lowest total price we've seen. (It's also $229 under the lowest price for a new one today.) This quadcopter features a flight time of 23 minutes per charge, 4K video recording, 12-megapixel camera, and 3-axis gimbal. A 1-year DJI warranty applies.