Summer and New Year are the biggest sale time in Japan. Especially New Years, most of the shops do events called "Hatsu-uri", literally means "first sale of the year", where lots of things get 20%, 30&, 50%, even 70%(!) off. Also there will be "Fuku-bukuro", lucky bags sold, where you can get variety of stuffs in a limited budget. Sometimes the lucky bag contains twice or third the price of things inside.