Amazon has the 6-Count Scrubbing Bubbles Fresh Gel Toilet Bowl Cleaning Stamps (Rainshower) for $4.67. Add two to cart (12-ct total) to reach $9.34 - 5% off with Subscribe & Save (cancel anytime) - $2.34 off at checkout (BOGO 50% off) = $6.53 with free shipping on $25+ or with Prime.