While browsing realoem site, I found out BMW has OEM RSE for X3, but it is mounted on the center console instead:
http://www.realoem.com/bmw/showparts...38&hg=65&fg=95
From the illustration on that site, I'm guessing it replaces the center compartment lid.
Further search on the bmw.com site:
http://accessories.bmw.com/internet_...&absoluteNav=1
They also have "tablet dvd" mounted on heardrest support, but IMO doesn't look that good.
http://accessories.bmw.com/internet_...&absoluteNav=1