With the release of Google algorithm updates such as Panda and Penguin, writing quality content has never been so important. Keyword Research is one of the main techniques you can use to ensure there is a high enough volume of searches for what you are writing about and that competition levels are acceptably low for these keywords. The problem with Keyword Research Tools in 2012 is that there does not seem to be a tool that does everything and comes at a reasonable price.
This post identifies several of the cheap or free 2012 Keyword Research tools to add to your keyword research arsenal."
From SEO Northern Ireland - http://www.seo-northern-ireland.co.uk/keyword-research/best-cheap-free-keyword-research-tools-2012/