OK two important things here:
1. India has taken Pu route for its program and the total cost includes following factors:
a. Cost of Fuel handling from Reactors
2. Cost of Fuel re-processing.
3. Cost of fabrication
on the other hand Pak uses enriched Uranium route which has primary cost of centrifuge plant. Now if the repost is to be believed, obviously Pak is doing it on a more efficient and economical scale.
Second, I read Army chief's interview sometime back and he made some interesting observations when asked about Pak stockpiling N weapons. He observed that any country's inventory is based on threat perception. for example analysts in India would believe that we may have to use them against both China & Pak in the worst scenario. However Pak has only one target and such an inventory doesnot justify the threat perception. It obviously believes that in case of a conventional war, it is near impossible to beat India (although it can inflict a serious damage). Thus you need to have an arsenal big enough to act as a deterrent and may be it has a Doctrine of limited use if situation warrants.
As for the numbers, As
Markus says take it with pinch of salt. what is important here is the amount of Pu available that can be weaponized. more importantly in modern times you don't need Megaton monsters. If unfortunate situation arises all we see is limited use of strategic bombs in order of few hundred (or less) kilotons.
