If you really wanted to go to WDW for "cheap" you can do it. Below is a 5-day trip budget for four adults going during slower season (though busier season isn't much higher).
Airfare: $250 x 4 (buy on a Wednesday)
Car: $25 x 5 (carrentals.com + coupon. We just did mid-size for $10 a day)
4/3...