Can you buy land from the government so that it's no longer part of the US?
What, thinking about starting our own country are we, they always said you would amount to something, they just didn't know what...
They have tried that in Florida a few times. Ever heard of the Conch Republic? Didn't think so.
How would buying land in the US make it not part of the US? How would you transfer US land to another country? I don't think you understand the concept of a "country."