Hi, and welcome to the site!:)
I've got to be brutally honest, that sounds like a load of tosh to me, cover the cost of being built? That;s be a £7000+ deposit then please!!

Also what's this about it not being mass marketed? That's the first I've heard of that. It'd be like selling the Focus ST170 or Mondeo ST220 in limited numbers, and I don;t see that being the case.
There is no way a dealer can say that you would be first to receive one, for that to be true your deposit would have to be with Ford directly, and not the dealer. Sounds suspicously to me like he has tried to wow you with his knowledge, dangles the carrot in front of you (being one of the first) and then tried to get you to commit.
As I understand it there cannot be a waiting list for a car that Ford has yet to confirm the price of. Sorry to put a bit of a downer on it all, but I am very sceptical of what you've been told.