since your doing a small grow, its should be a potent plant like white russian ~
you can grow under a large cfl or maybe use a 70-150watt hps. depending on ventilation.
i would really advise you just to buy a cupboard and have a full drobe rather then a small space. unless you are trying to learn the ropes, but even if you are better to invest then waste money. it might set you back $800-$1000 but on our first harvest you could break even.
cupboard, carbon filter, 400watt hps,400watt mh, 2 fan 4-5inches, mylar a few other things and your done