Possibly I have some economist bias, but I'm used to idea of assessing cost effectiveness. In a few cases, when there was something like political debate in my country, I tried to google basic fact check to get a bit more nuanced picture. And usually I failed. Sure, I found like some general info, like in attrition confrontation SAMs tend to be more cost effective than fighters, missile boats than bigger ships, ICBMs than ABMs.

No, it can't be simply explained by everything being top secret, as it was no problem to find many declassified documents on seemingly more touchy issues. It seems that if that was the case, then I should at least find some out of date studies.

So the question: Are cost effectiveness studies regularly done for weapon systems?
(If "YES", then where I could find such, possibly older, declassified ones? If "NO" then why they are rarely done?)