Vuvuzelas, the iconic horn of the 2010 South Africa World Cup, are mostly made by Chinese manufacturers. According to National Business Daily, 90 percent of the Vuvuzelas at the World Cup are made by plastic factories in south China's Zhejiang and Guangdong provinces.

"From the beginning of the year until April, we have produced over 1 million vuvuzelas," said Wu Yijun, manager of a plastic manufacturing company in Zhejiang. Wu said that there are only four to five companies that produce vuvuzelas, and they are mainly located in Zhejiang's Ningbo and Guangdong's Shantou.

Lin Miaoyun, sales manager of Guangdong Guangda Plastic Toy Factory, is also busy organizing the production and sale of vuvuzelas. Her company produces over 20 different types of World Cup vuvuzelas, which are sold to overseas markets including Holland, South Africa, Brazil and Korea.

"We started making soccer fan products years ago, but orders used to be very small," Lin said. The 2010 World Cup turned things around for her company. "Orders started to grow since last September, and we've been very busy with the production of Vuvuzelas from last November to March this year," she said. According to Lin, now all orders must make full payment first. Even so, her company has been working around clock to meet these orders, she said.

Despite the high market demand, Chinese manufacturers have a profit margin less than 5 percent. "The factory-gate price of vuvuzelas is between 0.6 and 2.5 yuan," Lin said. However, at World Cup games, soccer fans pay 20 to 60 rand (about 17.7 to 53.1 yuan) for a vuvezela. Most of the profits go into the pockets of overseas distributors and exporters.