We have three people in our family--husband, me, and 13 y.o. son. I go to Market Basket about every 3-4 weeks and spend roughly $300-350 there. That includes eggs, cheeses, low cholesterol margarine, yogurts, milk, deli meats, whole grain breads/pita breads, cereals, hummus, fish, chicken, ground bison, 100% juice, cleaning products and toiletries, beans, rice, natural peanut butters, lots of veggies and fruit, and occasional wine or beer. Then I fill in on fruits, veggies, and sometimes fresh pork tenderloin at a little market in town in between the big trips. I also buy bulk spices in town as well.
When you add it all up, we probably spend about $150-175 a week, including food, batteries, light bulbs, etc. I don't use coupons because they never seem to have the things I tend to buy. I don't buy much preprocessed stuff at all. But I do watch for regular items we buy that are on sale.
I tend to buy Market Basket's generic brands whenever possible (TP, cereal, whole grain tortilla chips, etc.) which really saves a lot and they taste just fine (not the TP of course!). And if I go to Shaw's I try to aim for the things that are on special. But I just go there only 1-2 times a month for little fill-in things that my little market may not have or if I have several veggies I need.
All-in-all, I must admit I'm not that careful about my buying. We love kalamata olives, sun-dried tomatoes, artichoke hearts, and items like that which can add up quickly. I buy some organic, but not entirely. But I do stock up when chicken/fish are on sale.
When I was on my own, before marriage and our son, I used to get by with much lower costs per month! I rarely ate meat and ate many more grains. Plus, I didn't buy wine or anything. Those all make a big difference (meats especially) in our spending. But I'm not willing to reduce my fruits and veggies intake. I'd be willing to drop the beer/wine but not sure my hubbie would go for that. If we really needed to, I bet I could shave $100-150 off of our expenditures each month with more care while still getting the protein my family craves.
I have considered being part of a CSA (Community Supported Agriculture) group nearby, but when I ran the numbers, it was going to be almost twice as much for what we buy. I realized we buy a lot more fruit than veggies which the CSA doesn't grow. I really believe in CSAs but I haven't made that leap yet. Friends who are part of it say they eat a ton more veggies when they joined the CSA because they had to keep up with it all. Some day I'll take the leap, though.
We mostly cook meals from scratch other than an occasional frozen pizza and Annie's natural mac & cheese. Otherwise, we tend to cook from the ground up.
Hope this helps!