I am not on a shoestring budget but that does not keep me from being frugal. Goodwill and Salvation Army stores are great places to find fabric, old blankets to use for batting (picked up a wool army blanket for $5!) and I have a complete stash of 100% cotton shirts destined to become a quilt, will more than likely get more than one out of them.
I find fabric deals on line as well and budget accordingly for my quilting expenses. I buy a lot now so when I am on a fixed income I will have a stash of all I need, except thread which I don't like to bulk up on ahead of time too much.