thanks to all, my family have a good time in Blue mountains in Dec 2011.
Here, I would like to share my experience on going there.
Like all non-natives, I search the internet and get some tips for TA. I checked out the Explorer Bus and thought that it is very good.
HOWEVER, a friend in Sydney actually taught us how to do it much much cheaper.
1 Purchase a Multipass in Sydney. This allows different mode of transport within the zone on the day - unlimited. - we took a ferry, then a train to central then a train to blue mountain. The cost of the ticket is AUD20, which is about the price of this trip.
At BM, instead of buy all the tour bus tickets - we continue the trip using the Multi-pass and take trolly bus No 2 (which is the public bus) - and because we have the day multipass - It is "free" for us....
The bus goes to the major attractions - 3 sisters and Scenic world - and all the hotels at Katoomba.
Save a ton of money - the TOURIST EXPLORER BUS IS AUD 35 each! while we paid AUD20 incl the trip from Sydney!