Dreamworld Ultimate Stay and Play 5nt package (+ free pass) from Paradise Resort
I looked at what it would cost to stay there from Friday the 16th of August to Wednesday 21st of July. For two adults and two children(3-12 years) in a resort room that total came to $1029. That means the average cost per night is about $206. This isn't too bad considering that these rates span a weekend, breakfast is included for the whole family, and you've got a 3 day World Pass ticket (which on it's own would cost an extra $329.99 if you had to buy the "Holiday World Family - pass" separately).
Note: bookings need to be made by July 31st and the minimum deposit required on the package price quoted above is $203.