Navigation Update

Despite having bought my X5d in November, I see that I'm already a year behind on the navigation dvd. In my past BMWs, I never updated the maps because of the $199 cost, but I see there are people selling the 2011 dvds for a lot less. Two quick questions:

- can we update our navigation system ourselves? The manual seems to suggest yes, but when I go to teleatlas and plug in my model, it says the dealer needs to do that.
- Has anyone used a dvd from ebay or a place like http://www.bmwnavigationmaps.com/ to update their nav maps? Any issues?

Thanks for any help.