Cleaning Slr Cameras Perfect Tool Kit How Important Is A Cleaning Sensor Unit In A SLR Camera?

How important is a cleaning sensor unit in a SLR camera? - cleaning slr cameras perfect tool kit

I am looking for a Nikon SLR camera, but not self-cleaning sensor, which has some of the Canon Rebel. How big is the agreement? Can the lens of a professional cleaning if dust inside? Thank you for any input!