I have 14 ((10)) 30 rounders, and 2 ((10)) 40 rounders... I started stocking up when they were about $25, on up to about $40... They can still be found, but cheapest I see is $45 (for a standard 30 rounder).
That sucks, but IMHO, these are the best AK mags to be had.
Polymer, with full-steel reinforcement.
FYI, what is meant by 'full steel' is they are reinforced as per Bulgarian military standard. Which I find to be at LEAST on par with Russian spec, if not better. Full cage feed lips, locking lugs, down the front, and around the bottom.
This gives you a good mix of polymer and steel, which coupled together gives you a strong mag. As well as being a little lighter than the all-steel old school AK mags. Nothing wrong with all steel, but they are heavier. So I save a few ounces, and am not sacrificing durability; so win = win.