I replied this somewhere else but just a note that I was staying about 5 minutes away from Shinjuku station so I did stumble along into Akiba backstreets when I was there. Also, when I was in Osaka, I visited DenDen City! All of these places are probably the closest thing to what I imagined when I was young but my point remains that I expected loads of unique Japanese branded electronics but was surprised (and underwhelmed) to see the same Korean, Chinese and Taiwanese branded stuff I see anywhere else around the world.

p/s: I'm probably not your typical "foreigner" since my heritage is Asian, I speak passable Japanese and I had one of those pocket mobile wifi thingamajig (GlobalAdvanceComm) so that I could use Google Maps to find my way around.