I have been importing supplements from China for 15 years. Not exclusively, but this is where the overwhelming majority of supplements are manufactured.
You cannot beat their level of vertical integration and labour costs. Yes, a lot of the stuff they sell is cheap or fake garbage, but that certainly doesn't mean all of it is. People are sold this idea that it's all fake and cheap crap, because they want to obscure the fact that they are getting the products they sell to you from somewhere else.
The illusion is fading...