Actually the Louisiana Purchase was 15 Million dollars which is 376,614,159 today’s money for 530 million acres. Canada is around 2,467,270,000 acres so this is just an estimate, but it’d take around 1.9 billion dollars to buy Canada at the cheapest. It would actually cost 4.5 trillion to buy Canada sadly. I guess we have to wait for WW3 to see our options