There is another option for transferring designs to a pillowcase, although it will take basic sewing skills. So, if you are not able to do it, someone with a sewing maching can.
You can purchase pre-treated fabric in 8-1/2 x 11" sheets at craft & fabric stores. In the craft stores they are usually located in the textile art area, and in fabric stores in the quilting area. But if you don't see it there, ask.
The sheets come in different weights - poplin, twill, and canvas, I believe.
All you do is put the sheet in your inkjet printer, set with a hot iron (make sure that you do not spritz it with water before heatsetting, or the design will blotch!), and trim to size. Then you can attach it to whatever you want with a sewing machine. Or if you use the poplin/broadcloth, you can turn the edges under 1/4" and hand sew it on.
Just another idea for you.