I use a Zoo Med hood which is around 20 bucks for a 12inch version.
A Compact Florescent does not generate much heat like a standard bulb would. This would be good if you don't want to burn off humidity. Follow Gingerlee's reply on temp changes for these bulbs.

I run a 26 and a 14 watt compact florescent pair on my 18x18x18 and the plants are growing nicely. I cover 1/3 the top screen with glass to retain humidity and my day temps hit 78 and then drop to 70 at night.
I mist twice a day to maintain an average humidity at about 60 percent. (initial misting raises it to 80 percent)

Don