20-30B would have been about what I had estimated given the complexity involved for this project. I think 11B spread over 2 decades and some change was a pretty

20-30B would have been about what I had estimated given the complexity involved for this project. I think 11B spread over 2 decades and some change was a pretty good deal comparatively. Now I think that hindsight being what it is, if we had known that Starship was in the pipeline and this would be launching right when Starship is getting into production (considering JWST started development in the mid 90s), I would have said that we should be designing a cheaper/simpler telescope that uses this larger launch package. But that's all hindsight. For what the JWST actually accomplishes, it's an engineering marvel and given what we knew when it was being designed, I think NASA and the associated committees did an excellent job making it as cheap and large as it is. Now if we were to take what was learned from the JWST (a lot of innovative work on beryllium mirror design and segmented telescope design was done on this project) and were to design a new telescope today using modern technology, modern materials knowledge, and a launch vehicle like the Starship, I'd suppose we could make an equivalent telescope for 25% or less of the JWST's cost. Unfortunately however by the time this would be feasible, the majority of that money had already long since been spent using existing technology and techniques. This hypothetical cheaper telescope would also likely not be ready for launch if started in say 2015 until 2025 or so when the Starship would be considered safe enough for such a high value mission. TLDR: It was a good value for the era in which it was designed and built. It is limited by what NASA knew when they designed it. And if it was to be built today, it wouldn't launch for at least a decade after the design would start and you'd undoubtedly be able to make a similar statement about said design from "now-era" vs a hypothetical better value proposition from "future-era". Knowing what we knew at the time it was worth it and to wait indefinitely for the optimal time to start a design will always be a race of better vs perfect.