Last summer they offered a "Summer Splash" discount code on cans of Pepsi. Unfortunately for you, the discount ended 12/31/2003. But if you don't need the tickets anytime soon, you can wait and see if they offer it again. It was, by far, the cheapest tix I found for the average citizen.
You could check and see if they have any other discounts you might qualify for. I know there has been some talk about them offering a military discount. Or maybe AAA, AARP, teacher discounts, State of FL discounts might be something open to you.
Ask around over at the Community board here on the Dis. Unfortunately this SeaWorld board doesn't seem to get too many hits...................P