Building such an enormous structure would probably require treaty-level negotiations with the international community, for example. A $10 billion price tag, however, isn't really extraordinary in the economics of space exploration. NASA's budget is about $15 billion a year, and a single shuttle launch costs about half a billion dollars.
I want one of these, I really, really do, but the U.S. government couldn't buy a Coke for that much money, and "probably require treaty-level negotiations with the international community?" Statements like those make the whole thing look much more improbable than anything to do with the science. And, what happens if it falls down?! But I still really want one. A lot. Did you see the pictures? I want one.
