I picked up a Repti-Fogger, and have to say I'm quite impressed with it--you should give it a try. Put it on a good timer, and you can have it run at 5 minute intervals up to 15 times a day, and that should really help a lot with cage humidity. Compared with a normal ultrasonic humidifier, the Repti-Fogger actually came out on top, and isn't terrifically more expensive.