They are known to be the best mags available for the AR-15. Most durable, longest lasting, least likely to jam, stuff like that.
So they have become the favorite and everyone who shoots AR wants them, especially down south where they don't have to pin them.
So here is the story. Once upon a time, Pmag were plentiful. If you wanted any, you could usually find them in stock from your fav' dealer for a reasonable price.
When Sandy Hook went down, and the US started buying everything, and naturally the popular Pmags got all bought up.
Because of all the buying down there, the supply of them got compromised up here. So everyone that planned to buy Pmags, fearing the worst bought them all at once.
Next thing you know, there was none left. So people started fussing, trying to find Pmags. There were none.
Enter the EE entrepreneurs. They started listing their spares at a considerable markup. Typically $50 a mag.
That lasted a while, until the scalpers took over. Any new mags that showed up in stock, got instantly bought up by the scalpers, and again, listed on the EE for a considerable markup.
So, for the last few months, if you really wanted a Pmag, you either had to wait for stock and get lucky to snag them at the right time, or lube up, bend over, and submit to the EE.
The reason why they are a big deal NOW, is because the buying crazy is starting to quell down south, and as such, Pmags are starting to become more readily available again, at a reasonable price, from your fav' dealer. So now, everytime some show up in stock some where, someone feels obligated to post about it, at which point, you may notice they promptly go out of stock.
So, if you're new to AR's, and want a good solid 5/30 mag, the Pmag is an excellent option. Just as advised, avoid the EE. Scalpers should burn.