if there is 1 thing that you should spend the extra money on it's lights... do not skimp on the lights. you could go T5's or 400-600 watt HPS, you should look to spend about $200, get a digital ballast or 8 bulb T5.
or you could go CFL and have slower growth and lower weight... but i wouldn't
Dude to simplify go to lowes or home depot an grab 4-5 day lights 400 I'm not to sure how much it would go for but like the dude says above me don't skimp