Currently it is almost impossible to get one. First you need a tier 3 gun license including approval from local law enforcement. Second you cannot even get a license to manufacture them, completely illegal; so they are SUPER rare. Even if you find a fully automatic rifle (which I personally don't refer to as a machine gun) it would cost $18,000. A proper machine gun like shown would be incredibly rare and very, very expensive.
The 2nd Amendment to the U.S. Constitution gives the right to American citizens to own military grade weaponry. This means that you should not only be able to own machine guns, but also things as dangerous as unmanned drones and tanks and the such. This is a right btw.
Forget the licenses and fees, just come to Arizona, the state of true freedom. I can walk down to the gun dealer and pick out a machine gun, pocket pistol, Barrett .50 cal sniper rifle....ANYTHING. If you got the cash, we got the guns. Just make sure you can pass the background check.
As a Constitutionalist, I always lean on the side of the constitution. The Second Amendment protects gun rights and therefore your gun rights shall not be infringed upon.
Are you licensed and well trained and screened?