Dana, that is a great point that you bring up! One comment that seems to come up periodically is how expensive it is to eat in the Zone.
I think that there are some things that can be done, ways to work the Zone in while being on a tight budget.
Buy meats in bulk when they are on sale, then keep in the freezer. Less expensive alternatives to meat are: eggs, yogurt, cottage cheese, tofu.
Buy frozen veggies rather than fresh. Surprisingly, there may be more vitamin content in frozen veggies! And, again, buy what is on sale and stock up. Also, beans are still fairly inexpensive, as is tomato sauce. Tomato sauce is one of my staples. I may also buy canned diced tomatoes, tomato puree, tomato paste, and jarred spaghetti sauce.
Those are just a few ideas off the top of my head. I am sure that there are some other really good ideas out there, too.