We eat lots of rice & beans type meals. I know rice doesn't work every day for you, so you need a starch that would. But replacing meat with beans saves lots of money.
Using meat as a flavoring, rather than the whole meal, works too. We make a sausage & lentil stew, for example, where sausage flavors the lentils and makes them yumm, but it only takes a couple of sausages for enough for two meals. Or sweet potato chili
(Kathy, you can do sweet potato, right?)
Buying meat in bulk from a local farmer was great, we got grassfed, pastured beefalo for $3/lb when we bought a quarter (prices really range, so calling around is good). www.eatwild.com
is a good place to start.
For breakfast, blender batter waffles are fast, and whole grains are cheaper than GF flours, at least here.
For cost saving on GF flours you use a lot of, check out amazon.com subscribe & save (15% off their prices, which are usually pretty good).
We also just canned our own salmon, bought a big chunk at costco and canned it. Yumm, and way cheaper than canned salmon (especially if you buy salmon in bulk - we're going to go to the cost when salmon fishing is in season and buy in bulk now that we've tested the idea).
ETA: I also think it's important to have realistic budget goals, though. The USDA calculates cost of food for four different levels of food spending (thrifty - liberal). Here's the 2008 numbers:http://www.cnpp.usda.gov/Publication...fFoodFeb08.pdf
For your family (I think, not positive of the ages of all your children), even the thrifty plan is $660, and the low cost (next level up) is $850/month. And honestly, with all the restrictions, I'm thinking the thrifty level would be darned tough. So I don't see how you get to $600 a month without dramatically shifting the food you eat (see how your DH feels about beans every meal
...). Not saying it can't be done, but you might be happier figuring out how to average out at $900 - $1000 a month, say, and cutting costs somewhere else for the rest of the savings.
P.S. - what happened with the cookbook, btw? sounds like a good way to raise grocery money.