Interesting, but at that price you may as well just spend a bit more and get a full blown small-scale CNC mill. It's not like you need granite-frame accuracy for an AR lower. Plus you can make lots of the other small parts.
I guess I just don't understand the use case for a purpose-built mill that takes 80%s. If you are super paranoid and want lots of guns, then just go the mill + lathe route and build virtually everything yourself. I mean if you think the government will ban all guns, why would 80% lowers be safe? Start with raw billet.
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If you're looking to manufacture, then buying 80%s from someone else is unlikely to leave you much margin.
If you just want to produce 80%'s a bit more easily than a drill press, get something like the Easy Jig (uses a router).
http://www.80percentarms.com/products/80-ar-15-easy-jigHaven't used one myself (and no stake in it), but based on the video it looks to make the process pretty simple. At $150 for the jig and roughly $70/80% lower that's easily a dozen stripped lowers before the ghost mill is even bought. Free country so buy as many guns as you like, but personally I wouldn't know what to do with a dozen lowers.