Things are expensive. Even making things, if you want them to be high quality, using high quality materials, is expensive.

I tried to look up some fabrics online and holy crap, they're not cheap at all. I will say, though, YKK zippers are surprisingly affordable. In relative terms, of course, but I thought they were really expensive for some reason. I guess it's hard to judge, being that I have no frame of reference for the price of zippers...

Still.