Don't buy at Narita. Earlier this month, the same bottle of Hibiki 12 that cost ~Y6,000 in the city was Y10,000 (or was it Y12,000?) at the airport.
Also, vintage Nikka Yoichi is practically unobtainable at the moment, and the price of anything >15 yo has shot through the roof. NRT was advertising Hibiki 30 for Y250,000 a pop (>US$2000), and they were still sold out.