I'm starting to wonder about this whole lighting thing. Okay, I can see the value when starting seeds in a bedroom, corner closet, a section of the garage - things like AJ does. At the same time, I have some plants that are too big to keep under lights so I have them on a table, about two feet from a window. The window is covered with plastic (I live in a very old house with crappy windows) and the plants get only about six hours of direct sunlight a day, with a total of about 10 hours. They are doing as well as, and probably better than the plants under the lights.
Plus, I doubt greenhouses use artificial lighting. At least the ones I have visited don't. Their plants don't get leggy - they start them in tiny seed trays, let them grow until they are completely root bound, then put them in 4-inch pots.
Something to consider???
Mike