Does 10 billion for one mean that it will be 20 billion for two? Once it is designed, and the teams are in place to assemble it and run the thing, economies of

Does 10 billion for one mean that it will be 20 billion for two? Once it is designed, and the teams are in place to assemble it and run the thing, economies of scale should kick in. Would be nice if most of that 10 billion was a sunk cost, and for 20 or 30, we could send up 50 of these things.