Nanoda--

Well, I was thinking that once a colony is self-sufficient, insofar as that is possible, they could in theory declare independence from the mother country and go to someone else for supplies -- historically that is what Americans did when we had trouble trading with the Brits. Of course, some British companies continued to do so, for all kinds of reasons. But trade routes with France ad Spain were opened up after the Revolution, and that served the United States well until fences could be mended with Britain. (This is a terrible over-simplification, by the way).

The moon has a lot of stuff on it. The biggest resource crunches would be in heavier metals and water, methinks, unless it turns out there is more than we thought, no?