There is no upper-end to what you can spend in the "upscale restaurants". You could pay hundreds of dollars to get a morsel from a star chef... even more for the right kind of beef or sushi. If you try to get American food in Japan...
1) you'll pay much more than its worth. Ingredient import costs.
2) it won't be "the same" (I've heard from several sources that the spaghetti is bizarre and burgers don't taste the same unless you've had Hawaii-style hamburgers).
3) and the real question, why would anyone want to eat American food in Japan? O.O
The Japanese do enjoy American food (particularly breakfast) and they're nuts over mayo (god knows why) -- they put it on everything (anyone remember the Tsukasa dialog in the first Lucky*Star episode (mayo on natto?)?
Someone I know in Japan has described a Tex-mex restaurant run by a Japanese national who spent time in Texas and loved the food. Much has to be imported.
The Japanese did go nuts for a decade or so over "american" fast food crap... but they seem to be reining themselves in and returning to traditional foods more often (and hopefully avoiding the descent into obesity).
They're also quite fond of curries and other "foreign imported then localized" dishes.