Don't know. Pricing is one reason why I will never buy retail systems (and, I guess, why I don't understand people who buy Alienware computers, for example). I guess a part of it is that you pay a premium for someone doing all the work of making sure that you get the highest-performance components for the price, that they're all properly tested and assembled, that they're compatible and that the system is designed to offer the best performance possible at that price level.
But I still think that they can be too expensive. Then again, I'm not a high-performance kind of guy, so I wouldn't buy that kind of machine anyways