Just to point out, I'm pretty sure you can buy a gun without a background check...from the government itself, no less. And it can be shipped to your door.
Civilian Marksmanship Program, a government chartered and supported organization, will ship any person eligible to have a firearm a military surplus rifle directly to their door. No dealer required. And you can get an M1 Garand, a semi-automatic, 10 bullet clip wielding rifle that shoots a 30.06 or .308 cartridge (far more powerful than a 5.56 from an AR15). It ships directly to your door.
Now, if its ok for the government to allow that itself, why is it not ok for others? And all that you have to provide to them is a certification that you are eligible to own a firearm (basically a signature), membership within a local firearms organization, and a certificate of some form of training. No NICS background check. Period.
Now tell me, where does your argument stand now? The government does it. And you want to criticize lawful citizens legally engaging in commerce to transact in privately owned property? Give me a break.
"You'll Never Walk Alone"