There's already an AK magazine weight thread in the archives, but I thought I'd add my own magazine weight comparison. My weights are slightly different than plouffedaddy/mrgunsngear.
These are all calibrated to my particular scale, so while they might not be perfectly correct, it will at least serve as a comparison as the others that are listed I weighed on the same scale as well. All were unloaded.
Toth Tool Mag - 9.9oz
Bulgarian Circle 10 - 8.8oz
Steel Spineless (country unknown, Chinese/Albanian?) - 11.6oz
Hungarian 20 Round Tanker - 10oz
Common Romanian or Hungarian (specific country unknown) w/ Spine - 12oz
If you're obsessed with saving as many ounces as possible like me, then I hope this will be helpful. Taking mag weight and price into consideration, the Toth Tool mag is top of my list right now.