The $50 Grocery Challenge

I have been distracted lately and haven't been focusing on my budget. I've overspent in some areas, and it has annoyed me. My husband hasn't been working this past month, and we are trying to budget based on what we think he will bring in the next 5 weeks or so, so that we have some left over.
I'm trying to tackle one thing at a time, and since grocery/food is usually where you can do the most cost cutting with some creativity, I am going after that first. We've already set an "eating out budget" for the month which is half of last month's expenditures. I hope we can stick to that.
With some "guesstimating," we think that on average, I've been spending about $100 a week or $400 a month to feed our family of four. I know I am overspending, because I haven't been planning every meal- and I have a surplus in our pantry. So we've decided to try and spend $50-$75 a week on groceries. I am not counting diapers or cat food in that approximation, but everything else counts. We'll be keeping track of random soda or coffee purchases at the gas station, because, let's face it, those can add up fast. I head to the store tomorrow, so I'll keep you posted on the damage, I mean my progress.