Here is a rough estimate by day at Disney. You also have to add transportation costs.
$200/night for a Deluxe with tax and with a discount
$180/day for tickets for 4 with a multi-day ticket
$100/day for food, drinks, ice cream, etc. (no fancy restaurants)
For a seven night, 6 days at the parks trip, with airfare (about $1000 for 4 for us) it costs about $4,500 to $5,000 with souvenirs and extras like minature golf. You can save on hotel, but you can't do much about food and tickets. Obviously, if you can drive, you can save on airfare, but we are too far away to do that.