As toomanybooks said, I'd be willing to bet it's taxes.

If you sign up for the Mousesavers newsletter, they send out a newsletter on the 15th of each month and they have a partner that offers about the lowest discounted prices.

If you know you'll be coming back again, it may make sense to buy a big multi-day ticket with no expiration date, really lowers the average cost per day (and protects you from price increases in the future). We're heading there in February and a 10 day parkhopper with 10 water park admissions (so 20 days of activities) is $524 total, and though we certainly won't use them all on one trip, they don't expire (just don't lose them!!!).

As for a rental car, I can't tell you how strongly I'd suggest getting a rental car in Orlando so that you can get around to eat and shop, even if you don't want to drive it to the parks because of parking cost, you can easily make up for the cost with the savings on dining.