This is a subject quite close to my heart (and tummy) as I love food, as do the rest of my family (hubby and 2 kids - 3 and 19 months). We spend - wait for it - a grand a month on food and this is with me buying the specials (and doesn't include alcohol). I shop at Coles in Southgate and yes, we do have to buy nappies, wipes etc, but this only makes up around $50 of our monthly shop.
It seems the best thing to do is to shop around (as per caoimhe's post - with 6 kids), and I take my hat off to them. Maybe I am lazy, but I would rather hit one shop and buy everything I need, than go to several different ones. I find food over here so much more expensive than at home. Gone are the days of 2 for 1 offers on salmon filets in Sainsbury's!!!