just a little comment from one who has cut and sorted many fat quarters in her life....
A fat quarter is a half yard of fabric cut down the fold, so if the cutting is accurate, it should measure 18" x 22". When a fabric shop cuts a fat quarter for you, it leaves one extra in the shop. If the store can sell this fat quarter, great! If not, the store has lost that income from that fabric. So when you have the time it takes to cut and fold the fat, fold the other, and then see if it sells, that is what the additional cost is when compared to just purchasing fabric by the yard.
You must believe me when I tell you that fat quarters, though deliciously fun to play with and put into our quilts, become a major headache for shop owners. Those fat quarters will be refolded and neatened every day once they are cut. Storing them and keeping them organized is a major headache.
When purchased from manufacturers as a prefolded bundled group, the retail price comes out to be about $2.75 per fat when the yardage cost would be about $8.75 per yard.
Initially fat quarters were not sold as they are today, in full collection bundles. Appliquers loved larger pieces of fabric so they could get longer strips of bias for stems, as compared to a "skinny" 9" x 44" quarter yard. And for block backgrounds (12") - you can't get that from a regular quarter yard. Shop owners would take the last little bits from their bolts and cut them into fat quarters and you may have seen a little basket of them in the front of the shop. Now they are a major factor in a quilt shop's inventory and add to that layer cakes (10" x 10" squares), jelly rolls, and charm squares. The packaging and processing is what you are paying for - just like if you purchase a single can over a case, a half pint rather than a gallon, etc.
If you are using a pattern which calls for fat quarters, please read through the instructions carefully to see if you will be able to use regular (9" x 44") "skinny" quarter yard cuts, as they are not always compatable. A pattern the suggests stacking fats and cutting a 10" strip and sub dividing it into 10" square is not going to come out of a skinny quarter. If you are strip piecing quilts and using a rotary cutter, however, the longer skinny quarter is often more useful.
No matter what you pay, or where you get them, they are a joy to sew with and lots of fun to use, so I expect we will see them forever in the sewing community.
Lisa