I've just started quilting. So far I've only bought new fabric for the quilt I'm working on now. I've also bought used flannel shirts for my next quilt and if I see a fabric I like in the thrift store I'll pick it up for future projects. So far the daughter has claimed most of them. I also want to build a small inventory of different threads and other sewing essentials so I don't need to buy a bunch of stuff for every project. It doesn't hurt to keep an inventory of fabrics or other supplies you know you're likely to use on hand.
Rodney