Amazon offers Prime members the Crane Ultrasonic Adorable 1-Gallon Cool Mist Humidifier in Frog, model no. EE-3191 FFP, for $28.80 with free shipping. (Non-Prime members can spend $35 or more to qualify for free shipping; otherwise, shipping adds $9.94.) That's the lowest total price we could find $9. It features a run time of up to 24 hours, auto-off function, and a 1-gallon tank.