http://www.wormsway.com/detail.asp?sku=SPT120 this ballast lets you use two different types of light with one ballast, most ballasts do not. You use Metal Halide for veg, and High Pressure Sodium for flowering.

I have one of these and it is great, runs very cool. Buy a Metal Halide bulb 400W $30 at Lowes, and a High Pressure Sodium bulb 400W I got mine for $23 at Lowes, the cordset to go from the bulb to ballast $40 and a reflector of your choice, I have the lightwave $25 and it it pretty good, not the best, but it gives good light disrtibution.