1) Stop bumping threads unless you have something
new to add to the conversation. The Smiler mistake was corrected
repeatedly over the past few pages, so was Everest being the most expensive coaster. Speaking of which...
2) Slash that Expedition Everest number by 80 %, and you'd be correct. $100 000 000 is the commonly cited figure (CF's Records page and Wikipedia, for a start - it took me ten seconds to look up both), where did you find a reason to quintuple it?
3) While Everest is the single most expensive
coaster ever, it's nowhere near the single biggest investment. Radiator Springs Racers at Disney California Adventure cost twice what Everest did, at $200 million. But that's only single attractions. The revamp of Fantasyland at Magic Kingdom is cited by the
Orlando Sentinel to have cost $425 million. Wizarding World of Harry Potter, just across town from there, cost $256 million. And I'm pretty sure those aren't the most expensive projects out there either, since when Disney spends money, they tend to spend a lot of it. I'm willing to bet that the budget of Star Wars Land exceed both of the above, and Pandora at Animal Kingdom is probably up there too. And who knows what kinds of money are spent on the Chinese theme park boom...