Well, there’s this guy on Youtube that definitely looks like he has a back garden full of warmachines.
He was actually a gun maker with a FFL license, which is how he got all those machine guns. He just got off probation for marijuana charges, and is heavily suspected in the mysterious shooting death of his business partner. He won’t be producing anything any time soon, because with that felony charge he won’t be able to get a FFL again.
Class III FFLs can get ahold of machine guns at MSRP, rather than paying the higher collectible rate for pre-1986 civilian legal examples. It’s also not an easy license to get, for fairly obvious reasons.