Rare Earth reserves are overwhelmingly distributed in countries that aren't that friendly with us. China, Brazil, and Russia hold something like 80% of the world reserves. North America amounts to about 4% of China's massive haul. Because deposits are not concentrated, they have to process a huge amount of dirt - literally mountains. That and the separation process makes for an industry that is pretty rough on the environment, which is why we don't have much of it in the US anymore. It will be a lot more expensive to do it here and we will run out long before China does. There is probably some money to be made in the near term though.