Granted a drone would be cool but from my limited experience cheap drones produce shit pics. My neighbour borrowed one to assess his flat (loft) roof and asked if I'd like him to film/photo mine. He did but it lacked any real clarity and was a waste of time, but not my time.
Many estate agents now provide aerial pics, so it might be cheaper and get better results if he made inquiries with one of them to see who they use.