Normally, I wouldn’t try to tell anyone how to run a business. God knows, I’m not a very good businessman myself: I’m eternally optimistic, lazy, and not really motivated by money.
That being said, I am quite experienced as a customer of other firms, and so have this one simple tip to offer anyone selling high-ticket consumer goods:
If a customer comes to you, ready to buy, do not send them away unsatisfied. Even more importantly, do not tell them that, while you can no longer sell them the product they evaluated 48 hours prior and are now itching to buy, you will happily accept 20% of the purchase price in order to motivate you, the seller, to acquire another such item so that they might buy it later.
This is an especially egregious offense if the product is neither particularly rare, nor difficult to acquire from one of your competitors.
Failure to remember this simple tip may cost you a long-term customer.