Expatistan- This awesome site tells you the cost of certain products in various countries. You will need to use a currency converter (see below) to convert the cost to US dollars :)
If you're having trouble finding a cost estimate for meals, you can use this generic list as a guide
A simple "Best Restaurants in X" Google Search usually produces good results too!
If you want to learn more about the traditional foods in the country you are visiting check out: