I would buy 9 cars, stick $50,000 in each of their trunks, and hide them around the US. I would then announce the scavenger hunt (anonymously) and give hints to the locations. Once all 9 are found I would announce 1 more car is out there with $1 million dollars in it and that the location is hidden somewhere within the previous hints. Then I would sit back and watch the chaos and conspiracy theories that occur.