A best bet is the
Tide Total Care HE Liquid Renewing Rain Scent 100-oz. Bottle 4-Pack (pictured) for $38.70 with free shipping after you clip the coupon and buy it via Subscribe & Save. That's $9.68 per bottle, $0.10/oz., and the lowest total price we could find for this quantity by $10.
Be sure to cancel Subscribe & Save once your order ships to avoid being billed for subsequent shipments.