Shibuya... but i can't remember the name of the shopping centre. Tokyu Hands... or something like that.
Actually, there some good shops in Osaka (not Shin-Osaka) which is not far from Kyoto, but due my shit memory i can't remember exact locations. There's ferris wheel on a big shopping complex in Osaka which is a good place to look....also the markets under the train lines might help.
Sorry i can't remember the exact locations...i was there in May08, and i was drunk most of the time