The cost of a tow is based on distance and complexity. Explaining the cost up-front, especially if the tow exceeds just a few miles or is one of those complex hookups may help- with the sicker shock issue. Educating the customer on what is involved helps. I'm going to guess that services offered through AAA and other organizations have insulated some of the public from actual cost of a tow as well. Deliver friendly service and take care of the customer, keep them informed. Your cost isn't important to them, but good service and value are very important.