That is why, when I make quilts for others at their request, I make them buy ALL the materials and charge just for my time to piece it and if they want it quilted, it's extra and they buy the batting. It's the only way I have found to make nonquilters understand what all is involved in making a quilt.
The last time I went with a friend of a friend to Joanne's. She loved a certain fabric and when the saleslady and I told her how much yardage she needed for a full size bed, for the backing, at $8.50 per yard--she told me she had to rethink the whole thing.!