My question would be: Why not have a passport?. In the world in which we live it is the best form of ID. If you have it, it is good for 10 years and costs under $100. If you decide to go out of country you need one. If you decide you need to go to Chile, or anywhere else, tomorrow you can go with a passport. If you don't have one you WILL WAIT.
Well... it ain't under US$100, but I agree, everyone should have one.