I used to buy only what I needed for a particular quilt. Then I found out that I ran out of my fabric before I ran out of blocks. I carried a swatch of that material around for 5 years, trying every quilt store I went into, looking online, etc. Finally one day, my daughter said "Look on eBay". Whadda ya know, I found it on about page 6, my exact fabric, and just exactly the amount I needed to finish my quilt! Glory be!.
Lesson learned, I always buy more than I think I'll need. I can always find a place for the left overs (another quilt, a swap, another crafter or quilter) and now I never have to wait another 5 years to finish my quilt.
nanac