Spiderman is the most expensive ride in the U Studio history which costs over 100 million dollars to develop the whole technology. But I am not sure if it's the most expensive ride ever built. I remebered when Indy Adventrue came out in 95, Disney said this WAS the most expensive ride (100 millions) ever built (because of the ride system is so complicated). But right now I would bet on Mission Space or Test Track (it cost so much because the repair fee), and Tokyo is currently building the most expensive Tower of Terror of the three. (which is around 150 million dollars) Expedition Everest is reported over 100 millions as well so there's plenty of indications that show Disney does out-spend Universal Studio. The next potential E-Ticket of Disney potentially coming out in 2007/2008 will be DCA's "Incredibles" ride(based on pixar animation film) which they develope the kind of riding techology called "Robocoaster" for ten years. I heard some say it is going to built in about 150 millions.