out of stock Kellogg's Nutri Grain 1200 Grams X 4 Pack $17.88 (+ Delivery/Free for Prime Members) @ Amazon AU
Amazon have buy 3 get 1 free for selected Kellogg's products.
Each pack costs $5.85, but great value when you get 1 for free! Comes to 37.25 cents per 100gms
Coles/Woolies only sell 805gm or lower packs. Cheapest I have seen is at Woolies or Coles at $3.70 for the 805g packs when they go on half price sale, which makes them 46.25 cents per 100gms
Combine with Cashrewards or Shopback for cashback as well!