@thefury: yup NaN is absolutely right. I bought mine at OSH for about 2 bucks a piece. You want the kind without drainage holes.
Also, here's what's going on underneath the sphagnum. I cut a sheet of eggcrate to just match the inside shape of the tray and sit it on top of three lengths of pvc pipe. This allows you to fill the bottom inch with water and not have your plants sitting in it. I poke the sphagnum through a bit to make sure it can reach the standing water. I've done this for years to grow moisture loving orchids, so it only made sense Nepenthes would benefit from it.
Humidity update: turns out the old humidity gauge was broken. With my original settings, I was actually looking at 80-90% constantly. I'm now down to running the humidifier twice a day and getting 70%-85%. I threw a fan on there for good measure as well.
I LOVE that sphagnum/egg crate idea! Been trying to think of a way to do something with sphagnum to help raise local humidity... And just letting it soak in the water leads to a nasty mess... I like this idea much more!
I will say that I have been able to get a little bit of live moss to grow on the bed of dead lfs, which is a miracle as live sphagnum hates me. It only grows well for me in my talangensis pot. I can't for the life of me figure out what's so special about that one pot.