Distribute Articles - excellent technique to get to one-way links from relevant content (of course, links from text is much more effective.) This technique is quite simple and effective - write articles, publish them on sites dedicated to distribute articles.
A one-way link that come from content relevant to a specific type of sites - which can add another shade of your link profile. The links you can add to the text itself or to add link to the signature at the end of the article.
Apart from assistance rankings, this technique can bring you traffic to your site, because most of the pages on articles rated. Not bad.
Financial investment in this case is only for ordering article recipient content, which ultimately distributes your site on the various articles. On the other hand, it is possible if you have broad Knowledge in an area where you are engaged in, you can write your own.
Financial cost (if any) of time spent writing the articles are relatively low and definitely worth the investment.