You could cut your own "pre-cuts", but think of all the fat quarters you would need to buy to get the variety that are in the pre-cut bundles. I also think there is more waste when you cut something out of a pre-cut. The little pieces left would be usable only in a crumb quilt. With larger pieces to start with, they could be arranged to waste less fabric. But then you're back to the variety. Which is more important to you?