Thailand: From Ko Samet to Koh Chang

We purchased the minibus and boat tickets 2 days before departure. The boat from Ko Samet to Ban Phe was 50 bath. We took the 8 o’clock boat at least it was suppose to leave at 8… It actually left 20 minutes early. The minibus ticket from ban phe to ko chang was 250 each. The minibus leaves from the Ban Phe ferry port at 9:30. There is also a minibus at 11:00 however We wanted to leave earlier. Upon arrival to Trat We have been taken to a travel agency where we had to buy the ferry tickets to Koh Chang for 100 Bath. I am not sure if this was the right price.
The ferry ride takes about an hour from the mainland to Koh Chang. We got free transfer from the Ferry to White Sand Beach provided by the owner of the Accommodation what we pre-booked.