Meg,
I agree, I really like the live plant environments best for the smaller species. I have found that the most economical full spectrum fluorescent bulb is the GE Sunshine bulb. Just make sure that you check the label that is stamped directly on the bulb, as it should read Chroma 50. If it doesn't, it's not the real thing. It has a color temp of 5,000 K and a CRI of 90. That's very good for a bulb under $10, and it works great for plants. I use either the 24 or 48 inch bulbs, single or double depending on the size of the cage. For best results, the bulbs should be no more than a foot above the tops of your plants.

Kelly