If you sell to the residents of your area, you know your customers. You have more than an e-mail relationship. Their kids go to school with your kids.
But what happens when they don't buy from you? You notice them carrying Walmart bags, those ungrateful turncoats. Maybe they came to your shop, asked you for a brain dump of all your product knowledge, then drove to the city to buy the product.
How do you respond? My recommendation is to be generous and forgiving.
Some people might be reluctant to buy from you in the first place if they think you will be offended when they ask for a discount, don't buy enough, or just browse without buying. So they don't enter your shop or dealership.
Some people like business to be anonymous. You need to help them overcome that anxiety by making it clear, through words and non-verbal cues and actions, that the transaction is not personal. Forgive them when they stray. But be aggressive about wooing them back.