Well the prices could be tweaked alitle bit, maybe lower the gunboat price to just over 100 mil or so..
Price wise I am mainly comparing Battleships to Evolutions (The only major mod with BS' I've played) and their cap ships aren't nearly as strong, they die in about the time one of our fighters die, but they definately have the firepower of battleships.
As for the prices though, I personally think it should take a couple or even a few weeks to get a battleship, after all it *is* a battleship.
