I think customer service is important if your business is a niche (small community of buyers) or you likely have repeat business (wholesale). Since commodity products (pc parts, electronics, video games, anything with a upc or ISBN), by definition, is driven by price -- customer service is less important I think. You still need to handle shipping, returns, etc but answering product questions is not important. Some businesses go for the volume game, will ignore pre-sales questions and just go for the volume. Amazon essentially operates this way. They just happen to have a massive knowledge base which replaces customer service.