> Isn't there another way to find some place on earth (preferably an island) that will be outside international conventions? Wouldn't that be more viable and cheaper than seasteading? I wonder if there have been attempts to do something like that in collaboration with some government.

It has been tried.

http://en.wikipedia.org/wiki/Republic_of_Minerva

Tonga forced them off the newly created island with a couple soldiers, and now they and Fiji are disputing which one of them owns it.