Oxa via Amazon offers the OXA Ultrasonic 4-Liter Cool Mist Humidifier in Gray for $39.99. Coupon code "ET37BTK4" cuts the price to $35.99. With free shipping, that's $14 off and the lowest price we could find, although we saw it for $8 less three weeks ago. It features up to 16 hours of continuous operation, dial control, and auto shut-off.