The same is true with fabric. A mill may make a similar fabric that is sold in the large, chain craft stores as what they sell in quilt shops, but the threads themselves, along with the dyes and thread count will be different which will affect the same issues: handling, the feel of the finished garment and how well it washes and wears. Experience, if not trusted advice, will show you when to invest in the costlier supplies. I once made a beautiful dress that looked good until it was washed. My bargain fabric did not hold up at all and the dress was never worn again.
My most current lesson on value concerns paper. I had a Stampin' Up die (Home Sweet Home) to use to make a cute little house which was going to hold candy. I wanted the house to be gray but I did not have any Stampin' Up gray paper, nor any other brand of similar quality. I'm not speaking of truly thick paper, just something with decent body. I did have gray paper in a multi-pack of grays and blacks from Joanns and thought that would be okay.
Isn't this cute? The black door has a stamped ghost but out vellum greeting visitors. There is a spiderweb, also vellum, on the front and back. The light in the windows is a shiny gold paper behind the black window panes that were die cut.
Here are the sides and back of the house:
I left glue off of one side of the roof so that it would open for candy.
So what is the problem with this gray paper? If you look at the above images closely, you might already see it. The paper is so thin, the scored lines which were made when running it through the die cutter (a Sizzix Big Shot), are splitting open.
Live and learn. And don't forget to add gray paper to my Stampin' Up shopping list!