Petsmarts here sell reptitemp 500R for about $45, only $25-$25 online.
I keep water bowls over the uth only when the snake is in shed, as long as the uth is being controlled by the thermostat it's ok to do, but not until it's controlled.
Some people mist tanks, my thoughts on that are that it causes a constant up and down in humidity, not good imo.
Have you covered a good portion of the top to help hold in heat and humidity?
Do you have any over head heat?
tank sizes...
http://freshaquarium.about.com/od/aq...zesweights.htm