buying the kit is...eh...sorta silly. if you gather the parts yourself, not only will you get a full understanding of what's involved and how everything works, you'll save money.
zzp in my opinion likes to throw stuff together and forget about it.
don't be a cc08 and think a supercharger kit is going to give you x amount of horsepower just because zzp says so. you may see dyno graphs, hear great things, but there's no way to really tell unless you tackle it yourself. a project like this is a project, not an instant bolt on horsepower adder. good luck :D