And cheap mags are everywhere. I bought a box full (17 of them) last month for $4 each, all USGI and like new. They looked like they had been used 1 or 2 times at most, didn't even have any sand in them.
If they are marked CMI, check them 1st before you rely on them for anything other than range mags. You might need to polish out the inside of the mag body. Some of the CMI mags had too much parkerizing inside of the mag body and caused the follower to drag.
If they are marked MecGar or Beretta factory you made a great buy.