I disagree. When the client doesn't care, they usually thank you for your time and you never hear from them again. If they are asking you about the price difference, you still have a foot in the door. They're trying to sort out the range in price and what causes that, in some cases. That's your time to sell work. Saying nothing when they are asking you a question, and turning your back to an inquisitive potential customer is a great way to go broke.
If a person gets quotes from 2 tree companies that came strongly recommended to them, and you act like a cock, you can guarantee that will get back to whoever gave you a recommendation. See if they call you again after they raved about you to their co-worker then you turned around and ignored an honest question and walked away from them. Not to mention, they ask you a simple question about pricing, you ignore them and walk away, and the first company doesn't show up..... You just lost work that probably went to you by default.
Justifying your pricing is a must. We are business men. This is business. Acting as though the customer is a minion that doesn't rank highly enough to get a moment of your thoughts will surely ruin your business, regardless of the quality of your work. This is just my thoughts though, and maybe Im wrong. Ive been wrong before.