What's a fair price on a M16 lower or Mac10 9mm?

Too general on the M16..

Here's the pricing on MAC-10's -

http://www.machinegunpriceguide.com/html/us_subguns_0.html

I'm not sure if you would find any stripped, registered AR lowers. If I had a registered AR which I was selling I doubt that I would be parting it out.

MACs are generally up past $10k now. I’ve seen them mostly in the $10-$13k with some being offered as high as $15k. There are still some deals to be had slightly under $10k but those appear to be drying up.

M16s have a lot of range because there are converted guns and factory full autos and both Colt and other manufacturers. Plan on at least $25k for one. An original Colt M16 (as opposed to a converted gun) will be well over $30k.

Ruben here is the high end of the market, but he is reliable, shipping is included in his prices, and doesn’t charge tax outside Florida.

M10/45

Colt M16A1