We'll (2 persons) be arriving in Kata at the beginning of March and we want to make some day trips to Ko Phi Phi, Khao Lak, Raya & Coral Islands. I've seen that there are a lot of websites from where you can purchase those tours in advance (and prices vary quite much), but some people are saying that is cheaper to buy them directly from tour operators when arriving in Kata. Is this true? If so, can we find availability for a tour on site for the next day? (eg if we want to buy a tour for Phi Phi island today for tomorow, can we find availability?). Thank you in advance.