I am surprised no-one has mentioned Cannnondale so far - because of the cost maybe?
I built my roadbike from bits bought from various shops, ebay and other online outlets. It currently has a Cannondale CAAD3 frame ($200 ebay NOS), Campag Neutron wheels ($400 SH online), Campag Record/Chorus 9 Speed groupset (bought piecemeal and now running to around $500) with carbon seatpost and stem.
If would heartily recommend the carbon seatpost, stem and anything else that can dampen out the posterior effects of large diameter alloy frames and stiff aero wheels.
If I did this again I would probably buy a complete Shimano groupset off the shelf, not that my Record stuff doesn't bling and zing, but because it took me ages to collect the complete set of compatible Ergos, front and rear mechs, etc.
Roll on Tour d'France
Al G