Where can we go for a cheap holiday for one week in july from sydney?

My boyfriend and I want to go on a holiday in july (school holidays)... we just got back from a very expensive overseas holiday, so are looking for something more low key. Since it'll be winter here, we're hoping to escape and go somewhere tropical. We've already been to thailand a few times so please don't suggest it lol. He's a school teacher, and I'm a university student, so we can't go any other time. We don't want to spend any more than $1000 each on airfares and accomodation (max 7 nights). Any ideas would be great?? Thanks so much. Doesn't necessarily have to be overseas.