I have one of those brass 20mw red modules that Aixiz sells. Somehow the lens got a scratch on it so I emailed Aixiz to ask if they could sell me a replacement lens or perhaps one from a dead module. Chuck, at Aixiz, replied and said he would send me a dead module for free! Well, he didn't send me A module. Within a week he sent me TWO modules!!! Now I just need to figure out what to do with the extras!
I can't speak for others but I have had excellent service from Aixiz and especially Chuck.