[ponector]

How expensive in comparison to the nuclear submarines or nuclear carriers?

[ghc]

The Apollo program cost about as much as 22 Gerald Ford class nuclear carriers.

Amortized over the whole program, each launch cost the same as building 2 Gerald Ford class nuclear carriers, or $26 billion USD.

[JumpCrisscross]

> How expensive in comparison to the nuclear submarines or nuclear carriers?

SLS already costs about as much as a nuclear submarine. Per launch.

[XorNot]

At its peak the Apollo program was about 6% of US GDP.

[azernik]

About 4% of the federal budget and 6% of discretionary spending at its peak, not of GDP.

Still a very high number, but nowhere near the military-budget-levels you're talking about.