Whole Foods aims to adapt to changing organic scene     Whole
Foods Market, historically, has not competed on price. That's
been a successful strategy because its educated, affluent
shoppers assume that quality must just come at a premium.
They're willing to shell out significantly more for pesticide-
free pears and artisanal cheese than they might for groceries at
the Safeway down the road.  The price isn't simply a function of
the cost of goods, though. Whole Foods' profit margins have been
significantly fatter than the supermarket industry's notoriously
slim margins for years now, at around 3.8 percent compared to
the average of 0.7 percent. Investors have rewarded this: Whole
Foods' stock trades at about twice the price of its rivals'.
Some of that comes from a product mix that skews more toward
prepared foods, which command higher prices, but the chain also
benefits from a squishy perception cushion that prevents
customers from comparison-shopping quite as ruthlessly.  That
perception game has stopped wo