mathematics on cost of having more VLS and missile loads.
A large naval missile can cost any where from US$500,000 to US$4 million each. For simple calculation we take $1 million each as the average. Let's say if 16 more large VLS/UVLS cells are added, that would be $16 million per ship which is not much if your navy has only 3 or 4 ships with such missile loads.
However, if you plan to have 30 ships of the new class with additional 16 VLS cells more then the previous class, that is $480 million cost on miisiles. Then you would also need to have spare missiles to refill the VLS after the first one is launched. So your cost now stands at $960 million fleetwise, for 1 in VLS + 1 spare missile.
US$960 million is cost for having option of one spare missile for each VLS cells. If you are expecting a great war between two super powers, you might want at least 2 spare missiles for each one already in the VLS.
So now you have to allocate $480 million + $960 million = $1,440 million or $1.44 Billion just for the cost of missiles alone, assuming the average missile cost is $1 million each.
What if your average cost each is not $1 million but 2 or 3 million? The more advance the missile, the more likely you have to spend more.
Having more ships with smaller number of missiles on each ship may work better compare with having smaller number of ships with larger number of VLS, epecially when you have to expect a certain number of your ships getting sunk or damaged beyond fighting condition.