That's not small at all. You gotta figure once you flower them they can double or even triple in height. So then you're looking at possibly almost 3 feet tall plants. How much room you got in that tent? You have to account for your lights at the top and at least a few inches between them and the top colas. I've seen people grow 12 plants under 250w cfls and come out pretty good at harvest time. You won't get huge buds but you'll get a lot of buds so it's a trade off. The buds won't be incredibly compact either. They'll be fluffy. It's still smoke though. Besides, you might end up with 3 or 4 males, and then you're down to 3 plants. I think you'll be fine, and over time you can add more cfls if needed. If you're on a budget, I wouldn't worry too much about HID lights.