Judging from the miles of Duty-Free retail space they make you parade through on the way to the plane (and the greatly increased retail spaces in newly-built terminals), I doubt they're passing much of the tax savings on to the consumer. We've found decent alcohol values; Bombay Sapphire had good deals for quite awhile. The best bargain was our trip hone from Madrid; unusually, AA's in-board price on premium gin was decent so we bought 2 bottles- and the charge never appeared on our credit card bill.