It doesn't take all that much to be able to pull enough out of your stash to make a quilt. I pulled 10 pink, 10 yellow and 10 orange fat quarters, and a 2 yard cut for the main border and a 2 yard cut for the narrow inner border and the binding out of my stash. That'll make a queen size quilt.
The real trick to being able to pull all the fabrics from your stash for a quilt is the way you buy the fabric.