Amazon has 80-Count Persil Proclean Powercaps Laundry Detergent (Original) for $14.10 when you ‘clip’ the $3 off coupon located on the product page and checkout via Subscribe & Save (select the later date from the "First Delivery On" menu). Shipping is free.
Note, you must be logged in to clip coupons. Coupons are typically limited to one per account. You may cancel Subscribe & Save any time after your order ships.