You just have to leave no stone unturned. I was trying to get to the PSA minimum for free shipping and was looking around for more stuff.  WTH, I'll look at PMags and what do I find but black MAG217s (not MAG560s) in stock.  Apparently I got the last three they had for @$13.25.   They arrived yesterday and they are indeed the right ones - apparently NOS with an 8/12 born on date.

PSA still has them listed, though, with a "Temporarily Out of Stock".  Might be forth checking from time to time there - you might get lucky, too.

Surplus Ammo has them.  I ordered 5 of them the the other day...