I'm planning to begin doing, not exactly studio work, but stuff where I'm controlling the lighting. I'd like to use strobes, and I'm planning to go with a basic setup with three lights: key, fill, and back. My question is, exactly how much output is necessary? Subjects might include, for example, indoor portraiture and still-life. I'm not setting up a dedicated studio--not enough time or space. But I'd like to be able to go somewhere and set up my gear, expose some film, and take it down, without having to break the bank to get there. I've noticed that cost is approximately exponentially related to watt-seconds. So, yeah, what's a good ballpark light-output figure for occasional serious lighting in a quasi-studio setting?