I'm of the quite possibly mistaken belief or am misremembering that after the Uzi .22 mag design was finalized about 10-12 years ago, Black Dog Machine (BDM) did a run of 5,000 mags; and about two years ago, the last of those were sold off. Prices varied somewhat over the years, but was $19.99/e. for much of the time, but was higher for the last couple years.
(Per a relative of mine who spent years in the plastics business) it costs a fair amount of money to set up and test run the molds and plastic material mix, so when a product is finalized, plastic molders only make large batch runs. I speculate that BDM currently is using their manufacturing capacity on products with higher volumes and profits.
If I had Uzi BDM .222 smoke colored plastic 32 round mags for sale, I would ask $50/e. plus shipping.
MHO, YMMV, etc.