They are available for the F25 in the UK. The link below only shows up to F25 [2010-2015] SUV.
http://www.ebay.co.uk/itm/BMW-X3-F25...-/380613712828
You may have to research ebay in the US.
Edit...
http://www.ebay.com/itm/11-13-BMW-F2...-/151039093966
That link only shows 11-13 BMW F25 X3 Aluminum Running Boards Pair Set Side Steps OE Style Rail Nerf