If you have ever seen camping supplies, they ussually have "Emergency Blankets" they are ussually refletive enough to use just like Mylar, and I think I've seen in some pictures in here someone else uses them also. (the little square folds in the material is a dead give away) their usually a couple dollars each and are pretty good size.
I use 4' T8
bulbs wen sarting my plants, and then I use either my 400Watt
metal halide, or 600 watt
hps depending on needs. I have seen the T8's do perfectly fine for lettuce and greens all by themselves and you can get them very close to the plants, even right on top of them if you have at least a small fan running over your plants.
Lately I've heard more people using the T5
lights, but their still fairly new and the prices on the fixtures and bulbs are a little higher for now.
There are tables on the Hydroponic Lessons on the site that talk about lighting, and needs per square foot etc. check those out.
Good Luck!