Okay, I have pieced together a 400w hps system by buying a Sun System Ballast on ebay and believe it or not I found a hood system at the local thrift shop for $10.Now what I need to do is get a bulb. I see that there are cheap ones and some that cost quite a few bucks.I guess what I want to know is what is the difference? I am not concerned about the cost but I want to make sure that I get one that is going to have the most effect. There are a couple of hydro shops in my area (I have a 6 plant Bubbler system that is vegging under CFL's right now) that have a wide variety of bulbs and of course Home Depot has a 400w bulb that is around $28.I will greatly appreciate it if someone can help me out.