[Windborne]

I think it's too pricey but 1000 would be too cheap, the trait is just too useful, with it subject populations never grow unhappy, and your people don't care what you do, you have complete freedom to play in a totally macavellian manner, manipulating the situation in any way you want without worry that going to war or making peace will upset your population or that a recently conquered planet needs a ton of troops to hold down the natives.