Cabela's is currently having a sale on PMC .223. $5.99 / box of 20.
Use the coupon code REWARDSfree for free shipping on orders over $49. That'll net you a case of PMC for under $300 / 1K. Not bad.
“The Second Amendment protects an individual right to possess a firearm unconnected with service in a militia, and to use that arm for traditionally lawful purposes, such as self-defense within the home.” Heller v. D.C. - June 26, 2008