save the time and money and get a 400 watt hps light. You could probably get one for about 150 bucks off of ebay. And just think you would spend about that much on a half a z of good nugs.
You wanted to know how many you wanted for a decent grow, I answered you. Wether you take my advice or not is your choice. but 8 bulbs aint jack shit, I've spent 750 so far and havent looked back, the results i get are way worth it to me, plus ill have the equipment forever excluding having to change a bulb every once in a while. It's an investment.