I periodically post about the idea of paying the Arabs to leave the West Bank and Gaza (also see here). Brian Gongol posted a fascinating analysis of the US Civil War showing that it would have been cheaper to buy out the South rather than it was to fight the war. He begs the question of how much the North expected the war to cost and whether it was rational for the south to fight it at all knowing that they were going to lose. But the math is interesting, nonetheless.
Paying to avoid war