Things needed to own a machine gun:
1. Live in a class III state.
2.Reside in a county or city (town) were the sheriff or police chief is willing to sign Class III paperwork.
3. Lots of money
4. Lots more money!
Cost of a machine gun can go for as little as $1500 for a Mac 10 to $10000 for a M-60 and everything in between. Most everyone dealing in Class III firearms is squeaky clean and above board. All machine guns have a paper trail. Best thing to do is find yourself a Class III dealer and have them walk you through the process.