The best way of spreading business is "word of mouth" through your satisfied customers. You can use Internet, print media & E-mail promotion, B2B ads and appointing agencies so on. But ultimately all buyers would like to do due diligence and positive reference is far better than all other media.
To do this yourself is almost impossible, the best option I've found is: Hire a team of webmasters, start related articles/blogs/content sites. Do proper SEO, submit to every related directory.
The results you can expect in the first few months: 1-10 visits per artcile. With 4-5 domains, with 30-50 quality articles/blog posts you can get 2000-2500 visitors per day, highly targeted for your products. The same amount of traffic from Google Adwords would cost you min. $250/day (based on 10 cents/click).