Musk put up the first $100 million for SpaceX ten years ago, money he made as a co-founder of Paypal .
He says other investors have put in another $100 million.
The company has signed about $4 billion in contracts for over 40 missions, both with private customers and NASA, and those agencies have come up with down payments. "I think we've received about $400 or $500 million in NASA funds so far," Musk says.
SpaceX builds nearly all of its own components in a renovated hangar in Hawthorne, California, which once housed Boeing.
Like Apple , the company believes in the importance of controlling the entire system. "I do think it's important to, well, I hesitate to use the word 'control,' but to ensure that the whole system is done right," says Musk. When asked why he hesitates to use the word "control," Musk replied with a laugh, "I don't want to sound like a control freak."