As a data point, I just picked up a post LCI 2011 e93 328i 6MT with 14K miles for $15K at a local BMW dealer. Included a 6M / 6K mile warranty for the price. Car is extremely clean inside, outside and under-carriage. The price felt right to me.
-- Dakota Leather, Cold Weather, Light Package, Premium Package, Navigation, Parking Sensors, among some others.
I'd say given it is a 6MT, the color and options, starting around $12K might be a reasonable place to list.
Good Luck!