Originally Posted by
msb0b
Big box stores are Yodobashi Camera, Bic Camera, Sakuraya, etc. They don't discount off MSRP, instead they give discounts in store points applicable toward future purchases. Every item carries a 3% 5% or even 10% of its price in points rebates. Signing up for a point card for a foreigner may be a challenge though.
The big boys have English-speaking staff who are happy to walk you through signing up, it's pretty painless. However, at Yodobashi you can't combine tax-free with points, so you have to pick one or the other (points will usually save you more), and you have to wait one day until you can use your new points for additional purchases.
Read through the warnings here before you buy any electronics gear, or you may end up with an expensive paperweight outside Japan:
http://wikitravel.org/en/Japan#Shopping