Open Air markets are one of the oldest way of selling goods in any culture.  Also one of the best ways to understand a local culture. These markets share a lot about what local economy looks like especially in a third world country.

Since supermarkets or grocery stores are only found in westernized cultures. The majority of world get their fresh produced from local markets. This is a great way to hang out with the locals and learn first hand about the local cultures and get a way from the tourist hot stop. Also you can get some pretty sweet deals on local fruits and gifts to take home.

This website ( Openairmarket.com ) is a pretty good resource to find local markets across the world and the US, but when all else fails ask a local.