Roughly double. For some, triple. Stripped lowers went for a 500 to 700% markup. $100 Stripped lowers were $500 for a cast, beat up no-name. $700-900 for a Bushmaster or Colt. And they sold like wildfire. Literally, in minutes.
It was a great lesson in human psychology, and supply and demand. The .gov said we couldn't have the "evil" features, and so people wanted them BADLY.
Another observation I picked up is that gun owners are such a law abiding lot. They all felt it worth while to pay the extra $700. rather then put the "evil" features on a post ban. Even though any charge or conviction for doing so would have been highly doubtful. Others cheaper or wiser (like me) just did without.
We better all concentrate on politics, because civil disobediance is not an option.
If the Black people of the '60's were like todays black gun owners, there would be no civil rights.
Not one of us had the courage to go to the front of the bus.