Have you seen H.R. 226, the cleverly-backronymed "Support Assault Firearms Elimination and Reduction for our Streets Act"?
It proposes a $2k income tax credit for turning in an eeevil "assault weapon" OR (and here's the important part!) for turning in "A frame or receiver that is identical to, or based substantially on the frame or receiver of, a firearm described in any of subparagraphs..."
This is what comes of people who worry about "shoulder things that go up" writing firearms law. Were this to pass, longshot as it is, I see a flood of battered Hi-Point carbines, OlyArms stripped lowers, and un-finished Nodak Spud AK project receivers coming out of gun safes and being used to fund brand-spankin' new Daniel Defense and Arsenal carbines. Poor Representative Rosa DeLauro (D-CT) might as well have labeled her proposal the "Milita Equipment Improvement Act of 2013".
Actually, given that Congress has the power to "provide for organizing, arming, and disciplining, the Militia," it'd be a lot more constitutional than Cash For Clunkers, in that the government has a legitimate constitutional interest in ensuring that there's a properly-functioning AR-15 in every gun safe.
EDIT: Arma Borealis saw it Friday, and immediately noticed the profit potential. I'm thinking of the way it could revolutionize discussion on internet firearms forums: "Ah got me this here Hi-Point 'cause Ah cain't afford one o' them there fancypants Colt 6920s." My friend, does Uncle Sam have a deal for you!