Cheaper holiday

Airlines:
https://www.skyscanner.com.au/
https://www.google.com/flights/
http://www.webjet.com.au
https://flightscout.co/au/

Accomodation:
http://www.trivago.com.au/
http://www.hotelscombined.com/
https://www.google.com.au/maps/search/syndey+hotels/@-33.8684706,151.2024925,15z/data=!3m1!4b1?hl=en
http://www.lastminute.com
http://www.wotif.com/
http://www.airbnb.com/

Guides:
https://www.tripadvisor.com.au

Deals:
https://www.scoopon.com.au/travel
https://www.groupon.com.au/travel
https://www.ozbargain.com.au/cat/travel

Free stopover:
https://www.flystein.com/free-stopovers/