Walmart offers the PureGuardian 10-Hour Nursery Ultrasonic Cool Mist Humidifier in Blue, model no. H900BL, or Pink, model no. H900P, for $19.99. (Amazon charges the same for Pink with free shipping for Prime members.) Opt for in-store pickup to dodge the $4.97 shipping charge. That's the lowest price we could find for it shipped by $9. It features a quiet operation, Silver Clean technology to fight mold and mildew, up to 10-hour run time on single tank, and low water level indicator.