I built a bike for $850 with a Bike Nashbar AluC frame (Kinesium tubing with carbon seat stays), carbon fork, FSA aero wheelset, Shimano Ultegra, Dura Ace & 105 components, carbon seatpost and it's great. It's smooth, weighs about 18 lbs. and would cost $2000 at retail.
I had to shop around for the components (eBay) but they were all new and it was worth it.