grow light bulb flourescent

Aquarium Lighting Questions?
Hi, the light I have in my aquarium lighting fixture (24" flourescent 20 watt) recently burnt out. I was wondering if it is worth the money to buy a better lighting fixture, one that could grow plants with a more powerful bulb even if we're not neccessarily going to grow plants that require additional lighting. Is it worth the $5 extra for better lighting?
You need 1 watt of fluorescent light per gallon to keep a plant alive, 3 to make it grow a little, and 5 to make ir grow well. I would check the Yamatogreen.com website; they are the plant experts. In my experience Philips Plant and Aquarium bulbs are very effective any fairly cheap/