I used to live off Robertson b/w Wilshire and Olympic. The cab fare (as long as not in rush hour) is around $35-40.
I agree the cab, or Shuttle service is the best way to go. Public bus is possible as mentioned but would take forever.
What time do you arrive - are you on 283 or 269? I would have offered you a lift but I have meetings in the office that day.
Have a good flight and time in LA.