I don't doubt that you could have a turbo kit for half the price.
What everyone here seems to get it is that this kit is already proven to work and you don't need to really "tune" it. Its more like a bolt on kit, where as a custom kit would take hours of tuning and sh!t that street flight has already done for you.
But whatever, I consider all turbo kits horribly overpriced IMO anyway but people like to stick with whats been proven to work.