Amazon has the 84oz Tide Ultra Oxi 59-Load Liquid Laundry Detergent on sale for $9.88. Click redeem on the Save 33% offer, then Add 4 to cart to reach $40 - 33% off multibuy promo offer - 5% off with Subscribe & Save (can cancel anytime) = $25 with free shipping on $35+ or with Prime. Roughly $6.13 each vs. $12.97 at Walmart. About 10 cents per laundry load.