Just before retirement I had occasion to teach a sales course to a number of in-house employees. Key to the program was:
1) treating customers right over time builds Customer Satisfaction
2) Customer Satisfaction over time builds Perceived Value
3) Perceived Value over time builds Customer Loyalty

Loyalty means that the Customer comes to you first--with problems, questions, etc. They want to buy from you, the focus on price goes down fast.
Lastly, it costs less to keep a customer that it does to get a new one.