Make sure you check out ERA:
http://www.erareplicas.com/gt/gt.htm
ERA's MkI, MkII and MkII Spyder GT40 kits come with all body components fitted and bolted together. Know up front that you must have a lot of patience and, well, money can't be be much of a problem.
Rounded off, the basic kit comes for $55K. If you want, ERA will do a turnkey or somewhere inbetween that and the basic kit.