I'll second Harvey's comments.
General tendency is eatern part is less expensive than western part of Tokyo (or suburb) - though it depends how far it is from central Tokyo and how far the place is from the nearest station - but if your working place is on western part of central Tokyo (Minato-ku, Shibuya-ku, Shinjuku-ku, for example), commuting from estern part let alone from Chiba or Saitama is a nightmare, as you have to go through the busiest are.