Holy crap, $58 for mirror glass is insane. I've become used to the electrochromatic auto-dimming glass here with Benz going for $600-900 a pop.
I've never heard of Boss racing branded parts, I'd say go for it at that price.
My dilemma is that I kind of wanted the new CF APR mirrors... but was just curious what the "BOSS" mirrors were, as it might have swaded me to getting those. The 20% off and free shipping really was the hook-line-and-sinker for me getting the APR mirrors though (been following them for nearly half a year and just got released).
It may have to do with not having the concave glass corners, but I am just speculating.