Spirits are dirt cheap in Japan, about half the price of Oz , even from the convenience stores. You can also get cheap Japanese drinks called chu-hi (does nothing for the head the next day though), mixed Japanese drinks in a can. These drinks are made from sho-chu, which you can buy straight, very cheaply, at any decent supermarket.
For food, try the Japanese rice balls from the convenience store or supermarket for lunch (they are called onigiri), good value for money (Chuck a couple in your pockets and take them up the mountain).
Cash all the way, Japanese carry huge amounts of cash on th