What you need:
Using measurements for a 20 inch IKEA pillow form, use 5/8 of a yard of fabric.
Cost: $10 (Without Tools)
FIRST, cut your fabric.
Cut one piece 20 inches wide and 52 inches long
Press your fabric with a hot iron. Fold the short ends under about an inch and then again another inch. Sew the double folded hem down with a top stitch close to the folded open edge. (oh and you pre-washed your fabric right?)
Fold the ends of the fabric over with right sides together (or on the inside) and overlap them about 4.5 inches.
Sew or serge up the sides. Use 1/4 inch seam allowance. If you serge, leave the tails. That way you won’t have to worry about the seam coming undone and no one except your laundry fairy will see it.
Turn it right sides out and don’t forget those corners! I have a point turner tool, but a semi blunt pencil works great. If your pencil is too sharp you may puncture a hole into the corner of your pillow case.