U can actually hear em start up too, u know its suckin some juice too. My power bill isn't outrageous anyway, think it went up like 5 bucks a month usin my lil 400w. but still, bulbs can be spendy, and though it is basically a money tree, personally, I do it for my own use, but then again, it's nice to know u could make some dough as well. Say my bulb burned out, shit better sell a little and get another asap. I should really have a spare now, gotta get one.