As mentioned, it depends on the lap. I use however wide the fabric is for the width (40-44?) and generally go for 60 in length if it's for a nap/couch size. If it is for senior lap quilts or wheelchairs, I do them 40X40 or however wide the fabric is squared. Flannel is a great fabric for the back because it keeps them from slipping off. As for price, it's hard to say. Small quilts or baby quilts are just not selling here even priced at $30 which just covers the supplies.