http://www.tactical-edgeusa.com has Pmags on sale for $10.99 for non-windowed mags! I know some folks like to have color matched mags, and I know I do, they have FDE, Foilage Green, and Blk all on sale for $10.99.
Ive ordered from these folks before and have never had issues with them, and every now and then, they do a nice blow-out sale like this one!