If you are thinking of buying a PC in Japan, the first place that comes to your head is Akihabara. That's where I bought my first PC from. But that was a mistake. Why? Because you can buy one for much cheaper if you buy online.
Why is it cheaper?
Two simple reasons.
Firstly, you can find the cheapest prices for the items that you want to buy via websites like Kakaku. One items could be cheaper at one shop but another item could more expensive at the same shop than another shop. You cannot go to every shop and not down all the prices. However, there are shops that are not registered in Kakaku.