I spend about 350-400 per WEEK on groceries and household items (ie papertowels, cleaning supplies, OTC meds, laundry detergent, vitamins, cat food, etc - all that type of stuff). There's 4 of us (DH, DS7, DS9, and me). We eat a lot of whole foods and produce. I have 1 son who has sensory issues when it comes to food so he will only eat what he will eat in terms of foods, brands, etc and so I have to buy his foods regardless of sales or costs. (This is a legitimate "medical" issue and he gets OT for it to try to expand his food options.) I'm pretty sure DS inherited this from DH, who is also super picky with his food choices.
It's super annoying and I wish I could cut back the total a bit. I've tried, but it just always comes out close to $400. So that's what I set aside - 1600 a month. Insane, I know. I do have a basement freezer that I can use to stock up on certain items, but perishables is where most of our money is spent.
When I see people spending under 300 a month for a family I'm so impressed, but I just don't see how I could do that!!