Hi,
One of the best things I like about this board is the "no quilt police". I belong to two guilds and they have their share of members who are "quilt police". I buy my fabrics everywhere and anywhere. It all depends on what I am making and for whom. There are plenty of fabrics in my stash that came from Wal-mart, JoAnns and even the Dollar store. I don't consider any of my work Masterpieces. If I am making it for a child I want it to be sturdy enough to hold up to rough use and lots of washings. I handquilt anything that is not going to be given hard usage. I judge fabric by the way it feels to the touch. As a hand quilter I am going to be touching it a lot. Many years ago when I first started quilting it was not unusual to put a sheet on the back of a quilt. With the advent of blends and the very high thread counts that are now available I would not recommend doing that unless you are going to be machine quilting.
A big part of quilting for me is collecting fabric and dreaming about using it. I have more plans in my head than I have years left on this earth Purchase any fabric that makes you happy and fits into your budget. Remind yourself it isn't fattening.