As far as the JoAnn's prices, I think it's just all part of the usual marketing gimmicks that they use. Mark it up to mark it down, so that the customers will get all excited, especially if they can use a 50% off coupon.
But consider... I've seen fabrics on their calico wall that they have priced at $9.99 / yard, and I know for a fact the wholesale price is $3.50 / yard. So they run them on sale at 40% off and the customers think it's a good deal. It's all a game... and apparently it works well, because so many retailers are playing it!