My humidity here in Indiana is around 40-45%... I've tried switching to Cypress mulch and misting daily, but the day/night lights I use for my ambient temps keep it dry. I've even covered 3/4 of the top of my screen top..
I was thinking about giving this a try.. An homemade humidifier

http://www.youtube.com/watch?v=d6Cgx4x0F_g

The only thing is the guy in the video says that this gets his humidity up to 45%.. I'm already there. It most be really dry where he is to be below 40% or so.