When Mr. C. and I were first married, $30 per week easily handled our grocery needs. As the children came along, we doubled our budget, thinking, "Twice as many mouths to feed, twice the expense." We didn't account for the increase in food prices over nearly 10 years. We also try to buy organic when possible, which drives costs up even more.
My generous estimate at this point is $500 per month for 2 adults and 2 small kids. (Tigaloo is nursing, and won't start solids for many months yet.) Hopefully my estimate is high, and we'll save enough to have a stock-up fund.
I don't really have anything with which to compare this amount. Does it seem high? Low? Since it's so much more than we used to spend, it feels high to me.