To add to what Andrew said:The best place to get the tickets is from Disney, but there are a FEW places that are authorized to sell tickets as well - such as AAA auto club. However, you DO NOT want to get tickets from places like Craig s List. Most often they turn out to be stolen, forged or non-transferable tickets that you will have to replace once you get there. For example, someone might have bought a five-day ticket, but then only used four days. They will sell you the extra day, but then when you get to Disney you find out there is a fingerprint stored in the system for that ticket and if your fingerprint doesn t match it, you don t get in... so you can t use that ticket.
The best place is at any of the Disney resorts instead of the regular paper type ticket, you get a credit card type ticket which makes for a nice memento for all the big bucks it cost.
If you are a member of AAA they have good prices.
Online at http://www.disneyworld.comor call (407) 939-7675If your only buying a 1-day ticket then you can also just go directly to the park entrance and buy them at the gate when you go. Have Fun!