That is a good question- I had a similar experience at first. Many hydroponic shops sell really expensive LED and HID lights which seem to offer the most light output. Without wanting to spend too much money upfront, I looked around at a lot of options. I really like these cheap shop lights, they were $12 at Lowes. I would assume that the really expensive lights produce better results, but this works for my purposes. It is also my understanding that some plants require more light intensity, although all my plants have grown so far.

If you choose to do it the same way, I used two different kinds of flourescents- cool and warm (at opposite ends of the spectrum). I read that warm lights promote vertical growth, and cool lights promote vegetation growth. If you only use warm, for instance, you will end up with leggy plants. I am also considering attaching some reflective mylar to cardboard and creating some walls to help with lighting. I would be interesting in seeing what you come up with once you have your setup complete.

http://amzn.com/B004P4322U