This is technically inaccurate. Machine guns may not be manufactured for civilian ownership since 1986 ( https://en.wikipedia.org/wiki/... ), however any made before that time are able to be owned by civilians, once the NFA is complied with. This requires submitting a $200 tax/fee to the BATF along with documenting paperwork, background checks, and waiting several months for approval (a right delayed is not a right denied? Where have I heard that before?).
As anyone who understands supply and demand will know, a fixed supply and decades of demand growth means the very limited number of NFA items (the actual number is unknown as the BATF does not fulfil FOIA requests as they claim they are not a "government agency") have risen in price from as low as $50/each at the time of the law passing to $30k-80k in the case of M16s today, depending on model and condition. So poor citizens can't afford machine guns, the rich can collect them if they see fit. More rare or fancy MGs, like a minigun are in the +$100k range. The cheapest end of the spectrum is something like a MAC10 for $5k-10k. Prices keep rising. ( Example prices http://www.autoweapons.com/pro... )
I should add because of their price and controlled nature, you basically never see a legally registered and possessed NFA firearm used in crime, it is just too expensive and a semi-auto does the job just as well. In some ways the banning of MGs has been allowed by both sides of the gun issue because it lets the anti-gun feel safer those "evil guns" are hard to obtain, and the pro-gun people can point to it and say, "see the really scary stuff is basically illegal".
Ahh I didn't think that there were any M16's available from prior to the NFA. I was mistaken and you are correct. But mostly I was commenting because it seems that the GP thinks that an AR-15 is an 'M16' that anyone can go down to Cabellas and pick up. It's clear he wants to ban guns without even really knowing what he is talking about. The same GP probably would freak out if a politician or layman suggested banning encryption without understanding what encryption really is.