I went to the estate sale of a woman who had owned a quilt store. Her house was filled with fabric and quilt magazines. The company liquidating had started selling by measuring the fabric, but the method was so inefficient, with a super long line and no dent in the fabric they just started guessing. By the time I reached the cashier they just looked at what I had and said...well, how about $xx? I said okay, paid up and figured out later I probably paid about .70c per yard. Weighing is definitely a better method, although a great deal is important also to a successful sale.