I've already done it effectively. 200 a month will be easy for me to stick to!
The biggest part of it for me is minimizing protein and vegetable costs. I won't be able to eat steak and extra lean hamburger every day.
I am still looking at about $3 a day on protein though. I am pretty much going with the following...
Protein:
Tuna(.33 a can)
Eggs(<$1.2 a dozen)
Milk protein isolate(cheaper than milk/cottage cheese/ff cheese)
Soy Isolate(I don't plan on using much of this though)
Poultry or Beef if they run a big sale
Carbs:
Oats(extra thick)
Brown rice(Lundberg)
Tortillas(you get tons of them for $1)
Pasta
Fats are for the most part dirt cheap. Peanut butter, olive oil, any oils basically. Fish oil I go with 2-3 g EPA/DHA a day. not too bad.
All that stuff ought to run me at most about 5 bucks a day, even with a little good meat thrown in everynow and then. With another 30-40 bucks I can get all the veggies and fruits I want. Just get stuff in bulk or on sale.
The key for me with the veggies is to buy them for their micronutrient content. i.e. go for variety rather than massive quantity and just get crap on sale. You might be surprised what you can do if you flat out tell yourself you aren't spending more than X dollars in a given week. I did that and it 'magically' worked out just fine.
I could probably go a lot lower than 150-200 if I needed to now. I like my specialty grains though!
Extra Thick
A lot of supermarkets carry those oats in smaller bags too. You can bet stuff from bulkfoods also though I haven't ordered from there.
-Cardinal