The final cost of an h-bomb at industrial scale was estimated at 10k in the 1960s (for low yield). However for practical purposes. One simply needs enough miss

The final cost of an h-bomb at industrial scale was estimated at 10k in the 1960s (for low yield). However for practical purposes. One simply needs enough missiles and warheads of sufficient yield to overwhelm opposing interceptors, avoid risks of pre-emptive strike/miss-fires+500. After that there are rapidly diminishing returns for more warheads.