1. I really recommend buying a used terrarium for cheap. You can get plexiglass cut to the size you want for a lid at Lowe's or Home Depot for very cheap.
2. You should go for fluorescent lights. That LED does not look bright enough and I can't tell if it produces the right kind of light for what you want.
3. Good idea going for the hygrometer and thermometer, though you can find cheaper ones at hardware stores for like $2.
4. I like the drip system, but you really will not need to spend that much money. You can put eggcrate or gravel in the bottom of your terrarium, put some water down there so it just touches the bottom of your pots, and in a closed system it will keep your Nepenthes moist for weeks. Plus, if you really want a small tank, that irrigation system will take up way too much room.
Are you going for lowland or highland neps? Have you thought about temperatures? Is this tank going on a windowsill or somewhere else?