Alternate Parks
Oh my! Did I just suggest you go to parks other than the four Disney World parks? Yep, sure did. Universal Studios and Sea World provide amazing entertainment value for much less money that the "Big 4."
In fact, Universal has a 2-Park Unlimited Pass that's only $99.99 plus tax for two parks for 7 consecutive days! Compare that to a 7-Day Park Hopper at Disney World at $286 plus tax!!
Alternate Activities
The Disney World Resort offers a fantastic array of alternate activities for your family to enjoy. You could visit a water park, instead of a theme park for almost half of what you'd pay to go to one of the main four theme parks -- and in July or August, you'd probably rather be close to water than stuck in the middle of a theme park, anyway. 
You also can just shop at Downtown Disney for free! Lots of great shops, including the largest Disney store in the world, World of Disney. Enjoy views of the lake at Downtown Disney, the pin traders kiosk, Christmas all year long at the Disney Christmas shop, and more.
Finally, don't forget about quick, fun activities like miniature golf, arcades at all the resorts, enjoying the pool-side activities, DisneyQuest, or catching a sporting activity at Wide World of Sports.