I stopped getting the OEM NAV systems installed when I kept getting billed $200 or more for updated CD's that you have to install. I bought an aftermarket NAV with 7" screen, free lifetime map updates, traffic updates and a bunch of other things for less than $500; came with everything to mount and even allows me to pair my bluetooth etc. Best investment ever.
Hit shopnbc.com, research the models and see what the web has to offer. Much better than OEM stuff...MUCH Better!