Does fabric make a difference? Yes. Let me answer my own question. When I first started quilting 15 years, I bought fabric at big box stores. I've sewn for over 40 years, so I know quality of fabric. I didn't buy any cotton that was stiff. If it's stiff in the store, it will be stiff in your quilt. Some of it never washes out soft. I would look for the better quality, tighter woven fabric, 15 years ago, the fabric at the big box stores was ok quality.... especially for beginning quilters. I had 2 projects I never finished purchased from a big box store.
I started buying at my local quilt store, (I love to shop clearance there) always wondering if there really was that much of a difference.
I recently finished those 2 projects from 15 years ago. Let me tell you what the difference is... the amount of lint that the cheaper fabric sheds is unbelievable! The cheaper fabric sheds lint like my border collie in spring! Also, it doesn't press as nicely as the more expensive fabric. I know it's not going to wear as well either, but if it's an everyday quilt made to be used, use it! The cheaper fabric also ravels more.
Buy what you can afford. For your beginning quilts, start out with the nicer fabric at the big box store if that's what you can afford. Make your mistakes on the less expensive fabric. If you have to shop the clearance at your quilt store, who knows or cares?
Be sure to clean out your machine, change your needle after 8 hours of sewing, but most of all, have fun!