I rarely buy it all at once. I purchase my focus fabric and maybe one or two of the complimentary fabrics. Then I go through my stash at home and often I'm able to come up fabric that compliments it well. I try to stock up on buying fabric for backings when I find a 'super duper' sale or clearance prices since you have to have so much of that. Should what I have on hand not work, I will try and buy some at the best price/quality I can find at the time. I remember Alex Anderson used to say on her TV show Simply Quilts, "Let the quilt talk to you. It will tell you what it needs." More and more I'm finding that to be true. As it comes together, you begin to get a concept in your mind of the kind of border it needs. Hope this helps a little. We keep learning as we go:-)