I switch out my pillows all the time. It probably drives my hubster crazy. I've seen tons of ruffled creations floating around, and finally made one of my own.
I took a large old white t-shirt, cut off the hem at the bottom, and cut it into as many 1.25" strips as I could. Then I sewed a long basting stitch down the middle of all my strips. My pillow is 20"x20" so I gathered my t-shirt strips up to measure 20" in length. I used a natural colored linen for the main pieces. Then I sewed the gathered t-shirt strips in rows on the front piece of my pillow- right over that gathered up basting stitch. I made an envelope closure on my back piece and sewed the two sides together. Old t-shirt + scrap linen pieces + reused feather insert = total cost $0