when i started quilting someone told me to always buy 1/2 to 1 yard extra of every fabric to 'build a stash', and here i am years later and many many quilts later with a HUGE STASH to prove it works.:mrgreen:
another friend told me always buy an extra fq sort of as a sample of the big piece. and yet another thinks if you love the fabric you should buy as much of it as you possibly can afford...and trust me, you will use it at some point...i dont' know about that one, i have fabrics that are quite old, and i still don't know what to do with them, but keep thinking some day the right project will come along...and i'll be ready.
really it depends on what kind of quilting you do, do you just quilt 1 project at a time, purchasing for that one then moving on? do you want your sewing room to look like a fabric shop? do you save scraps? do you use little pieces (fq's are enough) or do you do long row quilts?...it is all relative,
if you love it and think you will use it over and over buy lots, if you just want a little to remind you of each project get a fq. dont' worry as you make more quilts the stash will grow, all on it's own :D