I'm going to Tokyo in less than two months- it's my second time there.
The hotelreservation is made and paid for from home, but even so I still bring about 2000 usd's worth of jap.yen.
I go there to shop and explore and eat- but if you don't plan to shop, I actually think Tokyo is cheap!!!
Great food for little money if you like sushi, tempura and soba/udon!
If you are into rollercoasters you MUST try the thunder dolphin at Tokyo dome!
Enjoy!