I agree with NORMANTHEDOG, but if its your first visit dont get sucked into "free tickets for Disney" as you will be going to a time share presentation which will take all day and will be so far out of town you wont be able to get back until they bring you back and you will have wasted a whole day.
Also you can buy on line I believe.
i was there last week it is very easy to buy on the door and they have all the special discount passes as well - make sure you do the fast track for each ride that accepts it- you put your pass in the machine by the ride and it gives you a time to come back and you miss most of the queues it saves loads of time. The pirate of carribean ride is excellent