Yamada Denki (located on Hwy. 1 in Fuji near Shin-Fuji Shinkansen station, and other locations) has a point card system that can pay up to 10% of the price of your purchase in points. This point card system alone has often been for me the deciding factor in which electronics shop sells the same item the cheapest.
Sign up to get one at the service counter. And then every time you visit the store, play the game machines in the entry way to get 100 or more bonus points, too. One point equals 1 yen.
All that said, there are also Nojima Electronics in the big Aeon Town mall on Rt. 1 on the coast, and Kojimi Electronics in Fuji as well.