I think it would be much more cost effective to just go to WalMart and by a ReliOn ultrasonic humidifier and plumb it to the tank.
You get all the parts; fogger, fan, volume control, speed switch, power lights, cord, filter, etc. for under $50 U.S.
A couple of parts from the pumbing dept. (more then likely Home Depot Lowes, or local hardware store here, althought WalMart may have) a hose (or pvc pipe for hard plumbed) and your set.
I have several set up. They work best for smaller tanks....10 gal up to 20 or so. I do have one that I run to a 29 gal. This tank IS a open screen top thus it is run a lot to do much of anything. Kinda like a dew effect. This tank has tiger legged monkey frogs in it thus I don't usually try to soak everything down that much or that often.
The tighter the tank the better the effects. It may not replace a misting/rain system, it can help put a very fine fog into the tank however.
See the link to a picture on a 10 gal. luec. tank.
There is a resent thread with pictures showing what one person did to convert a Walgreens unit also.
http://gallery.pethobbyist.com/index.ph ... user=44240