I would just get her a garmin, but the Nav isn't the most important part to her. I think the main reason she wants it is for the iPod interface and the back up camera.
I recently bought a 2015 Tundra Crewmax limited with factory navigation, and after my wife drove my truck she now wants Nav in her 2011 4Runner non jbl system. Can factory Nav be added? If not are the factory looking units on eBay such as Casksa or Rosen worth it? I would just put a pioneer unit...