I'd be interested in that as well. The US program was expensive in part because they were trying to do it as quickly as possible, didn't know exactly what a fi

I'd be interested in that as well. The US program was expensive in part because they were trying to do it as quickly as possible, didn't know exactly what a finished bomb would look like and basically pursued every possible method for isotope separation at massive scale all at once. A program that just pursued plutonium production and separation to produce implosion devices would presumably be a lot cheaper (though still massively expensive in absolute terms, obv).