Depends. I built my Cannondale Six-13 around a used frame, mostly NOS Centaur and built my own Carbon tubulars. About $1300. I would never have found it already built, and even if I did, I think I did well on price by slow-build.
Campy Centaur, built 50 mm carbon tubulars using Chinese rims and hubs I had lying around, used frame. (front shown is a used Zipp, but the hub shell broke and I'm now using the homebuilt wheel)