I forgot to add one thing:
Aircraft carriers.
Most overrated warship of all time. Cost about 5 billion US to build, and that's not including the stores, computers, electronics... Plus the payroll of the 3500 sailors stationed on the thing. And it's absolutely useless without the airwing, and even then it's not much of an offensive threat. The airwing adds about 2000 or so to the total manning on deployment, plus their payroll.