By making them yourself, I meant you literally only need someone, anyone who knows how to use a sewing machine.
Yes, you can go to China for that. But we use a company 20 miles away to sew our soft goods, the proverbial sweatshop (it is actually quite nice). In the long run, sometimes it is cheaper to do things locally. I find this especially true if you are asking a factory to do something new. So check your yellowpages too before exclusively relying on alibaba.
As for material thickness, buy some samples from McMaster, you should be able to balance strength (thicker) with price (thinner) with your needs. None of us here are psychic, we don’t know the specifications you require for your product, you have to do that part yourself.