Welcome to the GT40 world.
There are really four body styles available .
The Mk1 is the most famous and the one replicated the most...in various guises such as the big flared tail of the Gulf car..
The Mk2 has twin rear air intakes behind the B pillar and also has small snorkels ontop of the rear deck.
The Mk4 is the only true American car to win Le Man ( built in Detroit)..it is a longer ,lower and a more squared off car with no carry over styling from the previous generations.
Mk3 cars are available but very very few were made and they are normally older lower spec cars from the UK...Ford built them as road cars and not very succesful ones at that.
If you are looking for a finished driving car then expect to start your search in the high 60's to mid 80's for a high spec current manufacturers car...
I have a couple of customers that purchase and build cars for resale ...feel free to get in touch if you would like more information..they are brand new high spec....
www.racecarreplicas.com
Good luck with your search...