Can a mod limit castle construction?

[Sombre]

You can't change castle prices. As I said above, you can't change anything about the castles themselves.

You could give people expensive castles after the midgame, but my feeling is even the most expensive 5 turns to build castle would get built by nations like Rlyeh. Plus it's a lot of effort to go to loading up and changing a mod just for a minor potential change.