I'm doing my first grow too. I started out with one light in a rubbermaid box with no fan. It made one hell of a little rainforest inside my box and was great for germinating, but I quickly learned that pot doesnt grow in the jungle. As well as the plant needing fresh air, its more an issue to have something cooling down your box.

You say you've got a grow light. What kind've light is it? I started off with a "plant light" which was actually just a big incandescent bulb painted blue, and was just way way too hot. What kind've light are you using?

If you're looking for a cheap meathod to use for lights and you're going to consider a box, then CFLs are the way to go for sure. Very cool running as not to heat your box. If your still vegetating you'll want to get daylight bulbs, or 6500K bulbs. I don't know how big your plant is so I can't say how many youll need right now, but certainly more than one. If you're already flowering, get some regular CFLs for their more red light spectrum.

Do you have any pics?