On average Hill's Science Diet Dog Adult Light 7.03kg is about $70. Budget Pet Products is sellling them for $36 + $14 shipping to Sydney so you still save about $20 compare to average price.
See below for price comparison:
http://99petshops.com.au/Search?Query=Hill%27s%20Science%20D…
http://www.dogfoodadvisor.com/dog-food-reviews/hills-science…
Not good for your dog.