I buy a half yard for variety, a whole yard if I really like it or it is a light batik as they are harder to find, and more (maybe a lot) if the price is right. I buy a lot online and just got 9 yards of a large Marcus Brothers floral print for $9 total- going to give the kaleidescope quilt a try. I love scrap quilts and have just cut up skimpily (not sure if that is a real word) cut FQs I got at a quilters' craigslist sale into squares to piece a backing- Bonnie Hunter style. Don't rule out Craigslist postings or garage sales to stay within your budget.