I just talked to the people who make the Germ Guardian. What you need to know before you buy is that the equipment can't be used to sterilize anything that is wet. That means you'd still have to clean and dry your nebulizers first. Also, from my microbiology training I'm a little skeptical that dry heat for 30 minutes will really sterilize things -- though it will probably kill some germs. True sterilization usually requires boiling for 20 minutes.
All that said, we're still going to buy the Germ Guardian. We figure we'll continue to boil the nebulizers, then shake them till they're not dripping, and put them in the unit, which should shorten the drying time to no more than 30 minutes. We like that the unit is small and covered -- should be good for keeping things clean in a dorm room.
I don't think I'd rely on microwaving a dry nebulizer to sterilize it. The CFF specifies microwaving in water (presumably to mimic boiling).
Bambi, mom of Jordan, 17 w cf