Seems like a reasonable price. I got 15k for my 2003 Imola/Black cab but with twice as many miles. Mine also did not have Nav, SMG and some other options you listed.
If you want to sell it quick, put it on ebay. No better way to determine its worth than to let the free market run its course.
Good luck with the sale.
A gen-u-ine BMW eff-eight-zero with them tandem clutches in the transmission and that dad gum sun roof on the top-a da cawr.