[Sangetsu]

You could live for two months on $3k if you were staying at a gaijin-house type dormitory, and there are plenty of such places located around the city.

Prices vary dramatically in the city depending on location. You can rent a 3 or 4 house in Nerima-ku for 150k yen, but that much won't even get you a studio in Chuo-ku. Outside the city the rents get even cheaper; my 3 room house in Chiba is only 60k yen per month, whereas my GF's 3 room apartment in Shinkawa cost more than 5 times that much.

There are apartment buildings in Roppongi Hills which rent large apartments for 3 million yen per month ($30,000). A penthouse apartment will cost quite a bit more than that.