I hate to be the bearer of bad news, but that kit is an absolute POS. The light is a cheap piece of Chinese junk with hardly enough power to light a cantaloupe (45 watt seconds). Even for one person, you're looking at a cost of roughly $400 for one decent light, plus stand, speed-ring, and soft-box-- and that's if you get a good deal. You might be able to get away with a 160 w/s strobe for a single person, but really you'd want to aim for one with about 300 w/s of power. Ideally, you'd want two lights. Shooting 8 people is a very tall order in terms of light power. If I were shooting 8 people, I would want several strobes with power ratings of 600 w/s or higher depending on the setting in which you were shooting and the style you were going for.
For budget lights, look at the following makers:
Dynalite
Alien Bees/ White Lightning
SP Studio Systems
Interfit
Sunpak
Some of my less favorite, but affordables:
Smith Victor
JTL
You could also try looking at these brands used:
Calumet
Hensel