The Dominican is correct - totally depends where you feel you HAVE to live, whether you will have the family etc.
In the good old days there were the taxis, they went years ago - now public transport and get re-imbursed so the cost not an issue but travelling time more so, especially if doing some 1 day trips.
Majority of trips start from Haneda (minority from Narita and inclined to use the ex JAL locals who live up that way but you will get some), just as an example if a suburb like Kamata/Keikyu Kamata was acceptable then 70 sq m unit around Y170,000, 12 minute train to Haneda, around 1.5 hours to Narita.
You need the bright lights of central Tokyo then Y250,000 won't get you far.
Personal thought is main consideration would be an area that has good limited express train access for Keikyu Kamata to Haneda and Tokyo/Shinagawa/Nippori to Narita (in Japan an express stops at every station, limited express only at some stations, go figure!)
Cheers.