Bradis has a large barrel of Pmag 30 rnds, I believe they were 15 or 16 dollars a piece.
joeboboufitters.com has them for $13 and free shipping over $90. Plus it's a veteran owned an operated company if that matters to you.
Magpul PMAG 30rd Magazines
Some will curse Botach for items being on backorder but I've been lucky. I think you can always call and see what they have in stock.
$12.73 each when you enter in the "MAGPUL" code. They also have free shipping.
Use the code "slickmag" and get them for $12 each shipped (20% off most Magpul products).
Buy local guys ! Support your local shops !!