In this video I show how to take a 400 Watt HID Metal Halide Warehouse light fixture and convert it to a grow light that you can you in your home. The same method can be used for high pressure sodium fixtures. These are verticle fixtures but can be converted to horizontal. I bought the fixture, bulb and new cord for $33.50 USD. I show where to look to find a deal like this.
Here is the link for part 2: http://www.youtube.com/watch?v=Xw96ydwtq3s