I've been looking at getting this 400 watt kit off of eBay.
400 Lumatek Grow Light Air Cooled Kit 2 bulbs - eBay (item 270295941520 end time Nov-10-08 16:51:28 PST)
Nice Lumatek 400 watt digital ballast, a 400 watt MH and a 400 watt HPS bulb, and it comes with a air cooled reflector. I currently have a 130 CFM squirrel cage blower exhausting my grow box, and I was thinking I could make a flange to adapt some 6" ducting to pull cool air through one end of the hood, over the bulb, and into the blower. I was also thinking about fitting the non hose connected end of the reflector with a DIY carbon filter, because once I hit flowering I'm going to need one. This setup will be used to grow 3 or 4 plants, all of which are in 3 gallon pots. I think 4 is the max I can squeeze in using 3 gallon pots. Currently I am vegging under 300 watts of 6500k CFLs. I'm just wondering if I remote the Lumatek ballast outside the box and then rig the hood to have cabinet air pulled through it if I could manage the heat.