In my opinion most of link builders are in or from India. A articles by India Book Staff to bring light on link building Industry in India and its future as lot of SEO world wide are now outsourcing link building jobs to Indian link builders. Only negative factor is dollar rate is getting weak day by day against Indian rupee.
In Indian there is tremendous growth in this business in last two year. Most of web solution provider has diversified there business into link building. Even SEO mainly into search engine optimization and position business now concentrate on link building job for major SEO in US and UK. There is tremendous increase in link building outsourcing business.