Don't think thats an M-sport, just a 540i/6. Still a fairly rare car but the description is a little sketchy. 400hp and 400 lb-fit of torque? Only upgrade seems to be a chip and exhaust... That would be a low price for something in mint showroom condition, but ya never know...
Theres a real M-sport for sale in the DC area, http://washingtondc.craigslist.org/n...617520217.html.
$12000 sounds more like M-sport pricing to me, might go have a peek at that one.