I think (and hope) that after a very long time waiting, that my upper is finally on its way. I now have everything I need to unleash hell except a rear sight. My upper has an A2 sight post but no rear. I don't really want to spend more than 50-60 bucks on a rear because I'm planning on putting an optic on it anyway. I just want it for a back up. I've been looking at the Magpul flip up. Is that the way to go? Any thing else out there in my price range? Not opposed to used either.