[bjourne]

15-30 mins in commuting distance is very optimistic unless you are able to pay through your nose. Think of it like this, if you earn an average salary then you can spend this much (pre-tax income) for living this close in commuting time from the city center.

  75% of it for living < 5 mins away
  50% of it for living < 10 mins away
  30% of it for living < 15 mins away
  25% of it for living < 30 mins away
  20% of it for living < 60 mins away
  15% for > 60 mins away

Adjust percentages upwards if you are desperate and downwards if you have enough funds to purchase an apartment.