Now imagine a busy professional who bills out at, say, $150 an hour. For her, the opportunity cost of shopping— what she could have earned by working instead of shopping— is destructive. Spend two hours comparison-shopping and that person has just lost the purchase price of the Palm Pilot V! While this will never be a problem for the poor, a rising tide of affluence works to inflate the value of lost time.
The same mechanism, by the way, is why urban transit systems have failed to compete with the automobile— the rising value of our time.