Have you considered using a misting system instead of a humidifier? I use the mistking starter kit. The timer that comes with it allows you to set 10 different times and for whatever duration you want. I have mine set at 9 seconds every 2.5 hours and my humidity is at 62 after misting and 53 right before it starts misting at my next scheduled time. If you buy right from mistking you can upgrade your timer for a fee and one of the upgraded timers let you set what humidity level you want instead of having to set certain times. Also the starter set allows you to run up to 10 nozzles off of just the pump it comes with, which then you could run multiple cages off on pump. All you would have to do was buy more nozzles and maybe tubing. It comes with quite a bit of tubing though.
From what I've looked at, the misting systems are significantly more costly than the humidifier and setup.