We are a family of three adults (63, 57, and 22). We spend between $175 and $200 a week at the grocery store (shop once a week), so somewhere between $700 and $800 a month this does not include eating out. It does include things like toilet paper, plastic bags, paper towels, dog food we buy at the grocery store too including occasional stamps, paper clips, shampoo also. I eat lunch at work at our cafeteria that isn't counted here, DS 22 gets free lunch at work, and DH brown bags it three days a week and goes out two (monies for lunches aren't part of this budget). We live in St. Louis county (close in suburb of St. Louis -- decent sized Midwest city area). We do not shop at the cheapest grocery store, but go to the one closest to our house, as we think the produce looks best there of the places nearby (pick store by best looking produce that is convenient). We buy what we want (especially for fruits and veggie), but do seem to have some price sensitivity (with beef so expensive mostly eat chicken with the occasional pork ribs or port steaks).
Dinners for DH and I are in except for Saturday night which is a tradition to go out. DS goes out more - modest places mostly, but social activity with friend / significant other.