So the tourists pay per parameter of their tour package, and then a lump sum for completion that's based on the number of parameters. In the below example, the parameter charge is 8,775, and the completion bonus is 26,325 per parameter (3 x 26,325 = 78,975; 4 x 26,325 = 105,300). So far so good. The first part that bugs me is they get to cheat on picking which parameters they want to pay for! Virtrude here, for example, wants to orbit around Kerbin, but doesn't want to pay for a suborbital spaceflight on Kerbin. That's a little like me saying I'll pay for the Tokyo bullet train, but I don't want to pay for the flight to Tokyo. The second problem is that it makes it makes identical flight plans cost different amounts. Compare Lezy and Barsan. Both want a suborbital spaceflight on the Mun, which I'd call the hardest (or maybe "furthest") part of the itinerary. But Lezy omits the orbit around the Mun and so pays less than Barsan. Both of them decline to pay for the orbit around Kerbin that'd be required.