The only way to acquire a military Humvee legally as of April 2015 is through a government auction of surplus vehicles. These auctions began in December of 2014.
The military HMMHV vehicle commonly called the Humvee is not the same as the civilian Hummer H1 SUV sold by General Motors until 2006, though the military design is the basis of the H1. Military Humvees sold through auction are stripped of military equipment and armor plating and come without titles. They are intended for off-road use only, and it is illegal to drive them on public roads, unlike the street-legal Hummer H1 models.