The low carb lifestyle is usually much cheaper than a "normal" lifestyle, because it cuts out all the processed food, brand name products and sugar-laden sodas. I just wrote an article on frugal low carb dieting - http://www.bellaonline.com/articles/art16210.asp
What are your suggestions for eating a low carb lifestyle on a budget? Really, most of what you do should be really inexpensive! You could eat eggs every day and never get bored, with the vast number of recipes that exist. Basic salad veggies are pretty cheap, from lettuce, tomatoes, cucumbers, etc. Chicken used to be a luxury item and nowadays it's one of the cheapest foods on the market! Same for ground beef.
The key seems to be to read your Sunday Paper for specials, and to Buy in Season. If you watch for sales, buy what's on sale and buy in bulk, you can easily save 50% or more on your grocery purchases.
Chime in with your recommendations! Our big recommendation is to buy chicken wings in bulk. Freeze the ones you don't use in one pound ziplocks, and enjoy!!