I bought a used booster seat at a garage sale for 50 cents. It needed a good scrub and the cover wanted washing but after a little work it was quite clean. Of course, I have two boys and I'm not personally a fan of girly material. I'm sure it would have been fine left alone, but then I wouldn't have got to sew.
An hour of cutting, trimming, ironing, sewing and guesswork later I had finished the booster seat transformation. I'm happy to report that my youngest loves his new seat, and I love it too.