8 at 1/4 power
yowzer. I'd get away from this kind of thinking.
The Adorama version of Goxox 360 sold for $310 with everything you need over the holidays, and is currently selling for 400, i think. As TeamSpeed said, a more powerful flash will get you what you want, much easier. One battery can power two 360 flashes, not that you'd want to do it that way, but you could. 2 360s equal 8 speedlights.



