I went to Etsy to see what pillowcases are selling for. The lowest I saw was for $4.99 for a travel case, too low I think for the fabric and time involved. I saw $12.00 for a travel case also and then up to $25 for standard pillowcase.
I just hope that you can get enough to cover the cost of your fabric and your time, even tho you had fun, you should get paid well.
warm quilt hugs, sue in CA