Worldwide, flea markets serve community-enhancing and economic functions. But have you ever thought about how they are "green" endeavors?
Flea markets use little if any electricity. They feature a lot of items that are handmade, or perhaps were once mass produced, but aren't any longer. Many other items in flea markets end up being purchased and "repurposed." Flea Markets are more pedestrian/people-friendly than they are car-friendly. They tend to be welcome fixtures in their neighborhoods.
Flea markets are good things for everyone to promote!