It's not always the case that the cheapest pre cruise tour is the one that is included. On our Rio to Lisbon cruise next March, our included pre cruise tour - 'Rio and Iguazu Falls' is listed at £3308 per person. The other available tour, 'a Passion for Rio' is listed at £984 per person. I guess it depends on a number of factors - how the cruise is selling, even what country you're booking from.