Don't worry about the sale — just take care of the customer. Give your prospect the best customer service you possibly can, even if he isn't buying. Eventually the sales will come (and come and come).
I have been writing about this concept for almost 30 years now. Harvard Business School's Ted Levitt once said, "The function of a business is to get and keep customers." However, these days, when I ask people what the function of a business is, most of them reply that it is to make money.
Making money is not the function of a business, it is the goal. If you misunderstand the function of a business (to get and keep customers), you actually make it more difficult to reach your goal (to make money).
Once again, I use the example of Ace Hardware, a role model case study for this concept. Here is a Good Samaritan story to illustrate:
Maria lives in Mesa, Ariz. Her eight-year-old-daughter Lisa picked up one of those color-changing mood rings in the mall and put it on her finger. Unfortunately, the ring was too small and she couldn't get it off. After struggling for an hour, she was showing signs of diminished circulation. What did Maria do? She went to the local Ace Hardware.