MEBuckner: Many of the programs (like the NASP) have government funding components, but almost all of them require the companies themselves to put up a big chunk of the funding. The X-33, for example, cost Lockheed-Martin close to 500 million dollars of their own money. Then it was cancelled. Undeterred, Lockheed is now bidding on the new Space Launch Initiative, which requires them to carry almost all of the burden (the government is contracting out the entire launch). NASA is basically just promising a guaranteed market - if you build it, they will come.
As I recall, didn’t McDonnell-Douglas build the DC-X rocket all by themselves? I believe the half-scale prototype was already flying when NASA announced the competition for the X-33.