For the case, just get a plastic soap dish. Drill some holes in the lid. Get a new kitchen sponge, cut to fit..instant redneck Planet Waves.
I like having a room humidifier also.
I use a room humidifier, since I keep all my guitars out. In the summer down in Florida, the airconditioner does a great job of keeping the humidity at good levels. In the winter, it gets drier, and if I run the heater, it really drys out the air. Get a humidity gauge and monitor it closely.
If you are keeping it in the case, then try a case humidifier. Plus if it gets really dry where you live, your sinuses will thank you for the room humidifier.