the ballast is in the fixture,the screw part of the bulb is larger then a regular bulb... I am going to buy one more fixture as the bulbs are not for sale by themself... Maybe the Home Depot bulbs fit this fixture,I have to check into this...

I think I found a 1000watt HPS fixture online for $119.00,I'll post the link as soon as I am sure the fixture comes with the bulb...

I still have to build my gro cab and get seeds so it will be a while before i test the wally world light...