I think I saw an alternative. I'll have to look for it though. It was some kind of medical pump/reservoir that someone attached to theirs and apparently works just fine. Since you have to hole with the droplets, you could add one on easily!
I also saw someone run a cool mist humidifier near their incubator. They said it was helpful.
Just love how the pump is integrated with the humidity sensor. I think the set up works really well. (but pricey.)