The 2009 Porsche Cayenne Turbo S that I might be buying doesn't have the backup camera. Is this something a dealer could do for me?

 

I am sure it can be done but probably cost prohibitive for the original Porsche camera. I don't know if you have seen one with it as it is an expensive & not too common option. The camera is motorized and pops out between the rear window and the Cayenne emblems. Therefore, new panels of the tailgate and painting will be required in addition to installation of the hardware. And I would assume only the dealer or someone who has a PIWIS can activate the PCM too. So, just a wild guess, I would say minimum of $3k to add it.