To actually make a grocery budget, it also helps to get an idea of what the family actually eats through per week.
In my house of 6 (4 teens/tweens), we eat, no joke, about 45-60lbs of produce per week. Just Wednesday at Aldi's I bought...
6 lbs of gala apples
3 lbs of pears
3 lbs of mandarin oranges
3 lbs strawberries
3 lbs red grapes
3lbs green bananas (my kids don't like them when they turn brown

)
2 lbs lemons
1 lb limes
1 pineapple (so 3lbs)
10 lbs russet potatoes
3lbs sweet potatoes
3lbs yellow onions
1 lb fancy green beans
1 lb asparagus
1 lb roma tomatoes
1lb green bell peppers (3)
1 lb baby carrots
1 celery (2 lbs)
1 iceberg lettuce (2 lbs)
8oz white mushrooms
8oz green onions
4 oz cilantro (I have a bag of avocadoes to use up from last week, so the green onions, limes, and cilantro will go to guac - this was about my only leftover produce from my last shop)
At 50lbs+, this will get me 5-7 days - I was lighter on veg this week b/c my friend is making us dinner Saturday and I'm ordering Easter dinner in and making brunch, so I'm only doing 5 dinners, or we'd have more veg (b/c lunch is fruit, and dinner is fruit and veg, with more emphasis on veg - and snacks are fruit, so more fruit does tend to get eaten

).
But knowing my fresh produce needs (I also bought cans of great northern beans, tomato sauce, and corn on the trip, since I had used those up in dinners last week - I only replace cans when needed), I know I have to hit a cheap produce store every week (either HMart or Aldi) b/c my regular store would be at least $1/more per lb of produce on average...and $50/week is worth a 2nd shop...
I could do the same list for "lunch and dinner protein" needs...and get an idea of what I spend and what I need. And in the produce list above, most of my items were the "deal" items or "normally cheapest price" items...I skipped squashes b/c they were not cheap for squash...same for skipping broccoli/cauliflower/kale...outside of bananas, I buy whatever looks good and is on sale...