Right, I believe it's more like 20 cents per KWh here, I'm jealous. It's also in the high 10s, low 20s(Fahrenheit) in my area right now, and we use radiators for heat, so with 2 600W lights I don't really produce enough heat to warm the house. I think I'll just get another 600W MH and exhaust the heat into the house like I've been doing, really wish those LEDs would work out though.
Brings me back to humidity, though. I'm gonna be using fabric smartpots which I hear raise humidity, but I always had to use a humidifier even with well vented grow lighting. Pain in the ass to fill every day and if I want to leave for a couple days I come back to a grow tent with a RH around 30%.