experiment: $6 swampcooler
mouse.mousetrap.net
This spring I was in a walmart somewhere and saw a Pelonis 1 gallon humidifier on clearance for $6. Walmart usually has the worst clearance prices so I was surprised to see it for 75% off.

a swamp cooler and humidifier of this design are doing the same thing: blowing air through a wetted, porous medium. The goals are different (humidification vs cooling) but the mechanism is the same.