Just a word of advice - I'd shy away from living downtown pittsburgh. Although there is a recent trend of people living downtown, and downtown housing seems to be on the upswing, dowtown Pittsburgh turns into a bit of a ghost town after 7:00pm. I wouldn't exactly call "unsafe", but you'd definately feel more secure, have more to do, and more conveniences in Squirrel Hill or Shadyside. The commutes from S. Hill or Shadyside to Oakland would be slightly shorter than the commute from downtown - contsant stream of buses during peak times, and can even walk when it's nice out <takes about 40 mins to walk to S. Hill, less to Shadyside>.
If you're looking for something on the cheap, you might want to check out Bloomfield, Friendship, Greenfield, or Regent Square - slightly less convenient, but can save a bundle in rent. Good luck.