I don't know if this trip can ever be repeated, but THE BEST (aka "cheapest") trip we ever did was in December after the Sept. 11 attacks, and everyone was too scared to fly or go somewhere like WDW... except for penny-pinchers like us.
We bought round-trip airfare from Nebraska to Tampa for $95, got a rock bottom car rental deal (can't remember the exact price) and a room at All Stars for $49/night!
On our way from Tampa, we got groceries and a styrofoam cooler so that we could eat all meals in our room, we carried snacks into the parks and had pre-purchased Disney items at Target to use as surprises for the kids during parades, etc. Super easy on the wallet. It was awesome!
The best part was that our kids were young and had never been to WDW before, so they were perfectly content with our low budget trip. In fact, on our last night while waiting for Illuminations, we decided to "splurge" and get something warm (Nachos) to share on a cool evening. DD 4 was thrilled and loudly exclaimed, "Wow, I didn't know they had restaurants here, too!"
Granted, I'm a foodie and I do love to try out different restaurants at WDW whenever I can. But if the choice is between going to WDW on a dime, or not going at all, I'd go on a dime.