What they said earlier, a 12 v adapter from an old phone charger. I try to keep the temp around 99, sometimes at night it would drop to 97 and I'd adjust the dimmer in the AM to raise it back up.
I made the same kind, My first hatch I had 4 of 12 hatch, I've got my second batch in ready to hatch any day now. I would put some holes in it for ventilation and I used duct tape to cover them to regulate the humidity. I can't really tell from the pics but I got a computer fan off of ebay for...