$30 for 40 amps is a great value for a low-end supply--plenty for a basic box, htpc, someone using even a mid-end card. I only have one computer out of five in my house that even needs more than 500 watts, so why pay more unless it is for a high-end gaming machine? One reason I like this website is that they will review all ranges of products, and I myself tend to fall in the value category so I can appreciate parts tending towards budget builds.
