Hard to say. Probably wouldn't want to dive in head first on an opinion of others. 4 grand should get you started but for professional photography you may want a hexa or octo copter ( for a DSLR camera). I would want something that was swinging larger props (at a slower rpm) 12" to 15" maybe and a 3 axis gimbal. A rock solid flight controller with GPS return to home capability that has proven reliability so you don't watch your investment fly away. A long range transmitter and FPV system with a camera that has pan and tilt capability (independent of the gimbal) from the ground station.
Check out this site http://cinechopper.com/ They had an interesting story that I read on another camera site that told of a fly away they had in the amazon jungle while filming for the discovery channel. These guys are doing it right. I think this is how I found them http://petapixel.com/