I bought some from CDNN. They are 8 round CMC Powermags without the markings. CDNN also had a few other styles that looked identical to other CMC mags... so I'm guessing those are too.
So just look for peoples comments on the Powermags and Shooting Stars. I haven't used mine much, maybe 48-54 rounds per mag as I've been working on my problematic MecGars I bought at the same time. But so far they're worked flawlessly.