Cool mist humidifiers range in size and, therefore, price. As mentioned, you could get a very small handheld machine, a whole-house humidifier, or something in between.; The most affordable units, which cost from $16 to $40, are low-end handheld models, smaller tabletop evaporative humidifiers and ultrasonic options with a small reservoir. For $40 to $75, you can find larger evaporative and ultrasonic humidifiers without a lot of extra bells and whistles that can handle an entire room.; For $75 to $200, you can find ultrasonic humidifiers with greater tank capacity, humidity sensors and other features, as well as freestanding home humidifiers. If you want an integrated whole-house cool mist humidifier, expect the price tag to be in the $350 to $450 range.