Unless you have an unlimited budget to drive your website to the top of the Google search, I recommend you use those tools that are free(other than your time) to generate quality traffic to your sites.
Take a look at The Power of Keywords for some good information.
Dot Web Solutions
--- Amanda Wickett Dot Web Solutions www.dotwebsolutions.com
What about the latest Google panda/penguin upcoming updates?Its rumoured all over the web that value of keyword will reduce after launching latest update.Is it true?