Being "stuck up" has nothing to do with the question. BMWs are known for their handling, road manners and build quality, not as much for speed. There simply isn't as much interest out there for aftermarket tuning parts as there is for other cars like the Mustang. The average BMW client is satisfied with the car as it is; they buy the car for what it is, not for what they can do to it. Therefore, there is not a big market demand for tuning stuff, so whatever is available is expensive because it doesn't sell in high quantities.