My original RealOEM link: RealOEM.com * BMW E53 X5 3.0d Retrofit backup camera
Step 1. Check the title of the page (of course, you probably won't notice the E53 written in nice big letters)
Step 2. Run a search on the part number RealOEM.com * Part Cross-reference (again, E53)

Some of the prices on RealOEM are outdated, some were wrong in the first place. However, being interested in mounting a camera and having checked with a local dealership, this is not the case and the price was roughly the same (roughly as in price was not quoted in USD and currency exchange may vary, and supplies in my area are by default slightly more expensive).

Now you can go back and watch Armageddon