Hi,
Bnuc is what you need for commercial, paid flying.
This will set you back around £2000.
DJI s800 with gimbal for sony nex will be around £5000 rtf.
The f450 is not really an indoor copter, prob a little big for flying indoors, in residential places its certaionly too big.
My advice if you havnt flown anything for a while and to get yourself familiar with copters and the dji stuff is get yourself this package-
here
or the F550 version.
Strap a gopro in and see what you think.