WeatherTech do a Tan coloured cargo liner which should fit in well if you have gone for the Beige interior. I have ordered a Tan one, not received it yet, will see what it is like.
http://www.weathertech.com/bmw/2012/x3/cargo-liner/
Stainless Steel rear bumper protector - bought the following:
http://www.ebay.de/itm/BMW-X3-F25-Ed...item25739614d6
received it but not fittede yet as do not have X3 until next week.
It seems really good quality, I needed one the covered the lip of the bumper since my current X3 is all scratched there and need to protect the new one when it comes.