Tokyo - Plarail what and where to buy?

Huge shopping joints like Harajuku will definitely have some discounted Plarail... here's some shops if it'll help:

Toys R Us.
Kiddyland – Harajuku.
Hakuhinkan – Ginza.
Yamashiroya – Ueno.
Tokyu Hands – Ikebukuro and Shibuya.
Tokyo Character Street – Ginza.
Toys Terao – Asakusa.