Patrick:
I recommend getting your park tickets ahead of time simply for ease. But with a little bit of homework, you can also score a discount on them!
Keep in mind that many of the discounted vacation packages from Disney require that you purchase your tickets from them (your room key will actually serve as your park ticket also--I love this convenience). Most of the time, the discount is on the room portion of the package, but, hey, if purchasing your tickets from Disney helps you save some money, definitely look into it.
If you're staying outside of the park or not purchasing a vacation package, you may want to look at a site like
www.undercovertourist.com which is an authorized Disney ticket seller. Our family has purchased our tickets from them using the discount link at
www.mousesavers.com and saved enough money to buy a tank of gas for the trip! You can purchase online from them or over the phone.
In addition, if you are a member of AAA, your local office also may have discounted Disney tickets. A few phone calls and a little research will save you more than you think!
Wishing you a magical vacation!
Whitney