RLV News posts about the continuing discussion at Space Politics on Mark's Centennial Challenge Lunar Lander proposal. Some of the discussion there is on whether or not there would be motivation to go after a difficult challenge where the cash prize is smaller than the team's cash expenses to win the prize. The RLV News post notes that America's Cup teams spend a lot of money on a prize without a cash component.
I'll also note that there are other reasons to go after a prize even if the cash value doesn't match the cash effort. A prize win can be good advertising, whether for an individual's resume, or a corporation's capabilities. A prize effort can also be strategic if the capability developed is useful to the company (eg: there's a market for the result, and the cash prize tips the cost/benefit equation over the threshold). There are no guarantees, but the mechanism has its place, including in the business world.