but is and should be more expensive so that it is not greatly preferable to adding new slipways to existing yards.
That they should be more expensive is not something I ever disagreed with. What I disagree with is if they need to be 10 times or more expensive to be balanced?
It is a question of gameplay vs verisimilitude, personally I prefer to err on the former side and not pay too much attention to the numbers under the hood so long as I understand the mechanics involved, but others approach the game quite differently. As I said, in practice I have found shipyard expansion to be suitably costed compared to other major expense categories. Increasing the cost of shipyard expansion would slow things down considerably as players will lack the economic means to expand very quickly, while decreasing the cost of building new yards makes it a lot quicker and cheaper to put yards into orbit. Neither of these are strictly bad things, but they do shift the game economy balance so making a significant change can have perhaps undesired knock-on effects.
The good news is that both of these quantities should be easily moddable if you want to test some changes, although the changes might not be easy to reflect in the GUI. For shipyards it is easy, just change the build costs in DIM_PlanetaryInstallations to whatever value you think is reasonable (I'd probably start by halving the costs - don't forget repair yards!). For shipyard expansions it is a bit of a hack, but in FCT_TechSystem you can modify the Shipyard Operations techs to effectively increase the costs by some factor. The vanilla values are 1.0, 0.95, 0.9, ... so you could change these to 2.0, 1.9, 1.8, ... and double the time and build costs associated with shipyard operations.
