A quick thought on coupons and giftcards:
They are ingenious. They give incentive for people who might not have otherwise spent money, to spend their money. That, or they direct sales to the store. In fact, giftcards are even better than coupons. Gift cards are all about directing future sales. Since people are given a $50 gift card to Best Buy, they have a $50 incentive to go to Best Buy as opposed to any other store to purchase whatever electronics. Best buy doesn't lose because they are sold the gift card for $50, and then they get the rest of the sale on top of that.