You can do it for free if you're a bit tech savvy. I've made a bunch of little changes to mine but it took some digging online. All you need is a couple USB memory sticks/SD cards and a computer with a hex editor.
http://avic411.com/index.php?/topic/...-instructions/
There are other threads on that forum that you might be interested in. You can do things like remove the nag screen, and turn on the 'safe mode' switch that will allow you full control of the menus while the car is moving. You still can't play video though when the car is running unless you move some wires around.