Is the primal diet or paleo diet compatible with "locavore" preferences and a limited budget? (It seems better to try the primal diet, even if one can shop only at mainstream grocery stores, than to continue a carb-heavy diet.) Is it ultimately compatible with sustainable agriculture? Can there be sustainable agriculture if the population in an area is too great?

Mark Sisson gives some advice for those who have a limited budget:
How to Eat Healthy and Save Money
Healthy Eating on a Budget
3 More Budget Friendly Healthy Food Tips
How to Eat Healthy on a Budget

(For more links, go here and scroll down to "Primal on the Cheap.")