
Originally Posted by
CelticPagan
Good question! I've often wondered this myself. Historically, the siege machines such as bolt throwers, catapults, balista, onager, etc... were built on sight and were made of readily available (or brought) wood and rope (sometimes metal for reinforcement). They are small and didn't take that much skill to build, unlike ships.
I guess you could edit the unit file's costs, but I don't know if that would mess up anything, such as scripts, that may be tied to that file.