Well, save for what those silly Sci Fi settings that claim that Destroyers are the biggest vessels may claim. And of course there's the general size increase of seafaring ships overall to complicate matters further.
The operating costs vs building costs are probably one of those things people (and the intellectually lazy members of congress) completely fail to understand. Something that costs 1B to build with 200M of yearly upkeep is actually more expensive than 1.5B/100M. That doesn't get into the potential bloat of each, but that's an entirely different topic anyways.