I want to like this, because lots of outdoor gear from reputable companies makes me wonder if they even test it, and markups are something like 4x (2x from China to wholesale, 2x wholesale to retail). But first you need to buy a sewing machine, and then there are the materials. You will be paying small-volume prices for a dozen or so items before you make something like a pack.
Have you ever thought to build your own piece of furniture, gone to Home Depot for the parts, and come out thinking you could have just bought one pre-made for about the same cost? Unless you have specialized needs and some free time, it usually isn’t worth it.