I use the one from Tredy. It's the 5L top fill ultrasonic one. $50 on amazon and it looks like there's a coupon for $10 off right now!
You need a humidifier/dehumidifier that restarts at the same settings after power is cut. Most digital humidifiers will reset to factory defaults after power failure, that's why I use this Tredy manual control humidifier. I have drilled a hole at the top of the unit and installed this type of float valve attached to a small 50gpd RO setup. I never have to add water. Works great for a 4x8 tent. As far as the dehumidifier, I just hook the exhaust fan to Work 2 and it pulls the hot, humid air from the tent. Humidifier then kicks on, rinse and repeat.
Nope! Mine is $50 on amazon and there's a $10 off coupon for it right now. Here's the link, in case you wanna check it out.