I believe the scratch coating at zenni is also a polarize as well, the use two different coatings I know of for sure, one is for the scratches, and Im almost 100% its the polarization is/was the 2nd. I know its there I will be getting my prescription sun glasses from. ive had mine now for 2 years, almost 3, never a problem, or even scratch on the lenses, I love that place, even got my oldest glasses from there and going to be getting my wife's next.
If not zenni, check the other places listed in the glasses thread in Hot deals, maybe the other 2 cheap glasses places do the coating if zenni isnt,