Help please :)

http://cgi.ebay.com/600w-Watt-MH-HPS-Air-Cooled-600-w-Hydroponic-Grow-Light-/400199229123?pt=LH_DefaultDomain_0&hash=item5d2dbb9ec3

after buying this, what else would I need if anything

Nice man, gratz...a good setup is one of the other things.
like white walls or mylar
good soil,
clean area,
some water,
organic food or whatever you are going to do.
a Oscillating fan or fans,
ph tester/moisture tester if you want,
timers
and of course seeds/clones
lil knowledge about growing

good luck to you

Now, you're going to need to buy a 6" fan/carbon filter combo, to take advantage of that air-cooled hood, and keep odors at bay.

thank you Jawbrodt i do not have one of those hoods so was not sure on that at all.

No problem man, just trying to help. It's a little pricey getting started, but once you are setup correctly, it's fairly maintenance-free. The only bad thing, is that the filters need replaced every 6-12 months, because the charcoal inside doesn't clean the air very well, after awhile.