Once on board, drinks can prove to be expensive and it's not as if you can go anywhere else cheaper. To some extent they have you trapped. They know happy holidaymakers will pay for a drink or two so the prices don't need to be driven down. Buying a drinks package with your chosen cruise line will see you making a saving. Also the same applies to Wi-Fi. Ask about pre-booking a data package if you really can't go without for the odd day sea.