If you are traveling alone or not taking conducted tour, you can also reach Sunderban easily.
There is only one comfortable way to reach Sunderban is by road only. There are may Buses plying everyday from Esplanade Bus Terminus to Sonakhali, Basanti or Canning. It takes about 3 hours time to reach all three places. The road is fairly good but thye buses are not. State Govt. run buses are slightly better but no Airconditioned buses for this route till date. After you get down at Sonakhali , Basanti or at Canning, you have to travel only by water transport as there is no road in Sunderban.
The fare for Sonakhali, Basanti or Canning is about Rs.120/- or USD$3 one way.
Then you can also go to Canning by EMU train it also takes about 2 hours. The train leaves from Sealdah Station and there are several trains throughout the day. Please remember the EMU are local trains only and has no toilet and always fully crowded. It's better to travel by road. At the moment the most popular entering point of Sunderban remains Sonakhali.
The best way to explore Sunderban still remains by boat only. You have a choice of boats available from Sonakhali port. The govt ( WBTDC) run conducted tours has large boats and can accomodate more than 100 people, they are the safest. These days fully aircondioned ships are also there run by VIVADA Inland waterways, I shall try to get the picture and the details soon and post them.
But even if you are traveling solo there is no need to worry. You shall get small boats to reach Sajnekhali as lots of shared boats ( Water Taxi) are going that way every day with passengers, supplies and tourists. There is a transport for every budget, or else how the locals are going to survive?