When Erika Dudra moved to Beacon Hill two years ago, she didn't know any of her neighbors. Dudra soon discovered a Facebook group called Buy Nothing Beacon Hill North. The premise of the group was simple: Offer up something that you don't need, or ask for something you do need. She joined to get rid of a couch, but then started asking for baby things. As a result, I have a 2-year-old now who basically cost me nothing," she said. When Dudra remarried ... she threw a "Buy Nothing wedding" with a donated dress, cake, decor, flowers, an American Sign Language interpreter for deaf relatives and a wedding photographer. To participants, Buy Nothing is about more than just fighting consumer culture, though. Today, all of Dudra's best friends are people she met on Buy Nothing. Since this network was started in 2013 ... members and volunteers have spread the Buy Nothing gospel to more than half a million people in 20 countries. Buy Nothing co-founder Liesl Clark likes to say the project is one-half internet giveaway group and one-half prehistoric Himalayan economics. Inspiration comes from high up in the Himalayas, where Clark has filmed archaeology documentaries for National Geographic and the PBS series "NOVA." In 2007, Clark visited a village in the Upper Mustang area of Nepal that didn't operate on currency. Instead, the village of Samdzong operated on a "gift economy" when a villager needed something, she or he would simply ask. Residents kept communal goats and sheep and took turns watching each other's fields.