Basically, you spend $75 for a starter game with 16 chapters, a game pad, and 3 figures, which will finish the basic game. If you have the Spyros game and pad, you can play the basic game.
Additional figures are about $10 each, with a minimum or 7 needed to get everything.
Then, there are 4 adventure packs -- called Chapter 17, 18, 19, and 20 (If you have the Prima Guide).
Look the game up on the internet, and see why Activision is making so much money on the game -- and why Disney is going to give a portal with figures a try, even though Disney cannot even do the simple programming of Epic Mickey games.