Why do both? If you offer quality with customer service, charge for it.
Limited resources of time, employees. If you are overwhelmed, raise the prices.
Commodities are priced different, the average customer doesn't know one brand of item from another, so they base the price of the commodity by price.
However if you are selling a commodity with customer service, then it is value added. Resources are limited, so the price can command a premium based upon quality, perceived customer service/satisfaction and retention. The value added portion consists of knowledge and expertise about the product. The product you are selling needs to be a complete package of quality, service, expertise knowledge along with ensuring customer satisfaction. That all comes at a price.