Sears offers the Ecosmart ECO 18 Self-Modulating Electric Tankless Water Heater, model no. ECO18, for $362.06 with free shipping. (Amazon has it for the same price.) That's the lowest total price we could find by $23. It features a digital temperature control and self-modulating technology and purports to save up to 60% on water heating costs.
Of note, Shop Your Way Rewards members will earn a Sears credit with this purchase and may be eligible for additional credits and discounts.