There are direct bus services from Dhaka to bandarban which leaves every night.
S. Alam , Unique , Dolphin Shamoly , Saudia, Shamoly are the bus service mostly starts from Fakirapul Bus Counter.
The fare for non ac bus is 430 taka (August, 2011).
That will reach Bandarban by early morning around 0700 hours (7.00 Am) if situation suites.
any one can go Bandarban by touching Chittagong.
Transportation at road, rail and air is available from Dhaka to Chittagong.
the link bellow may help one to go to Bandarban from Chittagong.
N.B. All financial data like fare, rent etc. based on the year 2011.