We, too, are eating off site this year, opting out of the Dining Plan. Always found we ate too much and lost alot of park time in the restaurants.
When eating off site last year, my wife and I often shared meals at lunch and dinner, as portions are generally large. You can definitely save money eating outside of Disney, esp if you are not big breakfast eaters. Take a visit to Target and stock up on snacks/juices/etc. to reduce spending at the parks. Many great restaurants within a 10 minute drive from Disney (esp. Bahama Breeze, Sweet Tomatoes, Chevy's, Houlihans) offer online discounts if you sign up with them ahead of time. Most restaurants are $10-$20/entree and have their menus online. Find other ways to trim the budget by: sharing/skipping appetizers, sharing a pop (free refills) and water, no alcohol (buy bevies at Target and drink at the resort), share/skip dessert at restaurants, make meals at your resort if you have a kitchen. Don't get me wrong, we will still spoil ourselves and eat at a Disney restaurant that we absolutely love.
Enjoy and hope this helps!