Depends on if you have to pay rent or you get a housing allowance. Rent prices are really high here, figure 600-900BD/month for a decent place.
If that's paid for by the company and you don't have to eat a ridiculous exchange rate by sending any money home, than you can get by nicely on anything over 1000BD a month.
if you have kids in school, have to pay rent, or have debts back home then it takes an ever increasing amount above that.