Tokyo is expensive the way many major cities are expensive. New York, London, Paris, etc. That said, there are ways to find reasonable prices quite easily, and you don't have to go over the top, just as in London, Paris, etc. The yen is pretty high right now which makes it a little harder, but what the heck!
The biggest challenge I have had in Japan was keeping my wife happy (a picky eater) while satisfying my own cravings for Japanese foods she wouldn't eat.