I have two now, best mattress I've ever owned, and several coworkers have them now too. Yet I am sure they are all made in the same factory as the rest in China. Zinus has expanded into related products like frames as well so I am sure its mostly marketing over manufacturing in China. Yet I've know people who spent $4000 on a Tempur-Pedic and didn't like it much. I'd rather spend $200 and not like it than $4000. At least with things sold on Amazon you can read 1000's of reviews which are unlikely to be all fake which at least gives you an idea of what people think, unlike buying a mattress in a store where the only opinion you get is the salesperson's.

Zinus sub-discussion from some time ago: https://news.ycombinator.com/item?id=15489344

I got lucky and saw the Zinus thread last year, I was close to spending over a thousand when I heard about them. I spent 400 for a king mattress and a stand. My Wife loves it!