Flourescent lights are the cheapest light to use. They run at about $2 a tube. They produce little heat so ventilation may not be needed unless the space is very small. The light spectrum put out by these lights is suitable for all stages of growing. Because flourescents disperse light over a large area, they need to be kept within three inches of the tops for the plants to receive enough light. This means you will have to mount the lights in a way that the can be raised everyday.