Ah... seeing the product on display is one thing, but finding the "cheaper" deal is a different story.
I don't know about Japan, but in Taiwan there's a pretty significant difference between gray products and those with Canon TW warranty. Usually the gray product is cheaper (though that depends - especially with the yen hikes), but there's the same problem of having to mail the lens back to the country of origin for fixes.
But then, I've seen Hong Kong lenses and US lenses in the gray market, so if someone from those countries get it here and bring it home, it MIGHT be a better deal... *shrug*. That's the question of possibility.