Wall Street Journal has a report stating that Disney has spent well over $100 million on the development of Disney Infinity. That's for both the game, and all of the toys that can work for it. Disney has had a very rocky history in the game development world, and if this game fails than things could be pretty disastrous for the company.
Except, I don't think Disney has anything to worry about here. Look, the Skylanders series has made over $1 billion in the two years that it's existed, which is impressive considering it was a brand new IP.
Disney is Disney. They have years of history that has created an insane loyal fan base that will buy the toys for Infinity for the collectors value alone. Plus all the methods of promotion at their disposal from movies to the Disney Channel itself. I'd be shocked if they can't pull in $1 billion in half the time it took Activision with Skylanders. Even faster if they ever announce a Marvel and Star Wars crossover for Infinity.
Disney Tries Anew to Raise Its Score on Digital Games [Wall Street Journal]