everyone will disagree, but if your looking to go cheep then get 1 or 2 cfls per plant, even low wattage ones work fine for me. but that will cut the energy bill down compared to using big MH or HPS. i know that teh MH or HPS would probably have a better yeild but clf is all around cheaper.

about space just go to the store and find a pot u like and do some messuring in your room u want to use.