Price goes down when the restrictions cease.
And, it conceivably wouldn't cost a lot of money.
I could easily see the US Government get forced into selling obsoilete combat vehicles by auction. They do that with trucks and other equipment already.
So, a lucky person could submit a low bid and buy one.
Not to mention the whole $$$ value is a moot point, as that is flawed logic at best. Back in 1934, $200 to register a $50 machine gun was considered enough of a financial deterrent to prevent ownership. Today, the $200 is just a small nuisance, as the better stuff costs in excess of $10,000.
Truth be know, I'd just as soon they simply adopt a particula state's firearms laws, with the restriction on silencers removed.
Check Vermont firearms laws, and there's a set of laws proven to work, without being overly restrictive. We've even got low crime rates up here.
CCW in Vermont? There is no law, never has been. It isn't prohibited.
Vermont laws on ATF Website. A very short read.
Add the fish and game law that prohibits a loaded rifle or shotgun in a motor vehicle, and you're done.