We spend an average of $200 per week on food for just DH and I... so about $800 a month.
We shop at Whole Foods for our basics and buy organic primarily. We buy our meat from a local butcher that only sells local, organic and grass fed/free range animals. I have an egg lady that I get our eggs from and I get raw milk from a local organic farm that doesn't feed grain or corn to their cows.
We are gluten free by choice, with occasional 'treats'.
I'm not sure how to slim down a food budget - we are of the mind that we can cut our budget in other areas because food is so important. We canceled our cable this year and save $75 a month. We downgraded our cell phone plan and save $35 a month. DH started taking the company shuttle to work and that saves us about $50 a month in gas. In the last year I've overhauled our household and completely stopped buying commercial cleaning products, I quit using make-up years ago, I make our soap, we don't use hair products, and I've purchased any clothing we need from Goodwill, CL or on super sale at Target and whatnot. Those choices save us TONS. A gallon of white vinegar, a bottle of Dr. Bronner's, a box of baking soda, borax, and some soap nuts are all I need to clean the house and do laundry - at the cost of about $25 every three or four months to replenish supply. I made some felted wool dryer balls to replace dryer sheets, and we got a clothes line to reduce the dryer use when it's sunny. We also really don't go out to eat much because we care about where our food comes from, so we save money in that area, too - I think we go out to eat once a month or so.
As for social situations, I'm getting more and more to the point where I just tell people we are 'gluten free' and let them either say, "Oh, okay." or ask me about it. Neither DH and I have any medical issues that necessitate being GF - but we've chosen this way of eating for better health and to avoid any future health problems associated with eating copious amounts of grains, so really it could be considered 'medical'. Like I said, though, we do allow ourselves to cheat on occasion, and because it's not a medical risk we just deal with some indigestion and grogginess when we do.
Also, because we purchase such nutrient dense foods I don't feel like we need to take a bunch of vitamins, so that saves us money, too. I'm just taking vit d.
I hope you can find a balance! As Hippocrates said - "Let food be thy medicine". Food is so important
Have you read Nourishing Traditions by Sally Fallon?