Jerry Pournelle has described a possible solution in several of his writings:

There is another way for government to stimulate technology development without dictating it: prizes. Pass this legislation:



The Treasurer of the United States is directed to pay the following sums for the following achievements:

To the first American owned company to build 3 space ships each of which shall achieve orbit and safely return once each week for three consecutive weeks, $3 billion dollars.

To the first American owned company to build a space station that is continuously occupied by at least 7 Americans for a period of 3 years and one day, the sum of $5 billion dollars.

To the first American owned company to build a Lunar Colony that is continuously occupied by at least 31 Americans who remain alive in continuous occupation of the facility for three years and one day, the sum of $12 billion dollars.

We can quibble about the amounts, and whether there is anything to be paid for second place, but the main principle is that nothing is paid until the feat is accomplished. Thus there is no risk to the Treasury, and the program doesn't compete with NASA or the services; and I think we can all agree that if the tasks are accomplished, it's cheap at the price.