You can make one really easy. You just need to slap together a wooden
frame with a bottom just deep enough to mount a couple flourescent
lights to, then cover the top with the translucent plastic they use
for the flourescent lights in drop ceilings. I made one with NO
carpentry skills for about $50. It gets the job done, and actually
looks pretty, too. Unfortunately, I had to leave it in my old
classroom, but the teacher who took that job still uses it, so I guess
it held up. :)