is peace cheap?

"There comes a moment in life when a choice must be made between right and wrong, between good and evil, between light and darkness."
-How To Make Love Like A Porn Star: A Cautionary Tale, by Jenna Jameson

Because I don't feel like wasting time, and for the sake of argument, let's all agree that Peace is a Good thing. That being said, I'm forced to reflect on the High Cost of Peace. Does Peace require a constant influx of large sums of money in order to maintain it? I've noticed that the united states, and many other countries around the world, have spent large sums of money to maintain peace through military spending, which only opens up more conflict. History means nothing, because if humans learned lessons from history, world peace would have been a fully-realized reality thousands of years ago. It seems like peace doesn't cost a thing- it requires no military spending. Would peace stimulate economies? World peace would make one world economy, all of a sudden eveyone's money would be worth the same. Why can't we just invent robots to work all the shitty jobs, so everyone can live comfortably?