New price low. Amazon has the 4-Pack of Crest 3D White Glamorous White Whitening Mouthwash (16oz bottles, Arctic Mint) for $21 -  $8 off coupon (check "Save an extra" box, eligible on first S&S order for this product) = $12 with free shipping on $35+ or with Prime (extra 5% off with 5+ S&S orders). Roughly $3.10 per bottle vs. $5.64 at Walmart.