How much would you pay for an egg? Fifty cents? Two dollars? How about $6,000?

That's how much it cost one restaurant in Newport Beach, Calif., which refused to honor a customer's request. The money wasn't lost through legal action or any formal process. Rather, it represents the lost business that eatery suffered — because of one egg.

Let me explain. Authors Deb and Todd Duncan, whose careers also include television production and peak performance training, detail the 10 new golden rules of customer service in their new book, "The $6,000 Egg."

Deb and Todd were frequent patrons at a chic test kitchen that experiments with new menu items. One day, the featured special was a waffle served with an egg on top. The couple wanted a cheeseburger, which was on the menu, but asked to have a fried egg added on top of the burger. They were surprised to hear from the server that the kitchen might not be able to do that. Sure enough, even though they were making eggs for the waffles, the server told them the kitchen was too busy. So they asked a different server who knew them well.

The answer was still no, because it wasn't on the menu. When they asked to speak to the manager, she approached without a smile. After yet another request, she stood firm, explaining the restaurant only orders a certain number of eggs per day, and they couldn't sacrifice one for a cheeseburger.

Todd was incredulous. He asked her, "So a one-time visitor who orders a waffle for $15 is more important to you than a $6,000 customer who comes in at least four to six times a month?"

Her response was a textbook lesson in terrible customer service. "If we run out of eggs, we can't serve the waffle." So when Todd suggested she might be able to send a busser down the block to buy a few extra eggs, she offered to cover their check for their inconvenience. He couldn't believe she would rather pay their $75 tab than sell them a single egg. They left, and vowed never to return.

They wound up at a restaurant next door, where they shared their experience. There, the server told them that their company creed is "We don't say no here." Guess where they go for breakfast now.

Many of the rules the Duncans include in their book are common sense, yet they are broken over and over again.

Perhaps the most frequent complaint I hear from readers is that they are repeatedly disappointed in the service they receive, even from companies they have done business with for years. Those companies would be wise to remember that one bad experience can destroy customer loyalty. Anyone in business knows it is much more expensive to find new customers than to retain existing ones.

Our motto at MackayMitchell Envelope Co. is: "To be in business forever." That's getting to be a tall order. Technology has replaced the need for envelopes in many cases. E-mail, text messages, Snapchat, online bill paying — you name it, another bite out of our industry. So we need to keep customers happy, because their options seem to expand daily.

You can have the finest products, the best food, the most incredible hotel rooms and the trendiest styles — but if you don't deliver quality service, you have nothing. Even in this instant-gratification world, customers relish personal service. They want to feel important. They want to know that someone cares.

Remember, most customers aren't asking for miracles. They might have special requests or needs that are not part of your usual offerings. But if you can accommodate them, do it. Don't make your customers walk on eggshells.

Mackay's Moral: Great customer service is the goose that lays the golden egg.

Harvey Mackay is a Minneapolis businessman. Contact him at 612-378-6202 or e-mail harvey@mackay.com.