Free listings vs. paid listings
Your most common search terms are already #1 ranked in Google's regular search results and your are wondering if you should advertise in AdWords too for the same keywords? Would it help you or is it just a waste of money?
Well, the answer is simple. You should do both, SEO for the free listings and PPC for a constant and reliable traffic.
Sure, free is always a great deal, but you should still buy PPC advertising as long as it will give you an acceptable return on investment. It's kind of like owning stocks -- some stuff gets you 15% interest this year, others makes you 3 or 4%, but you dollar cost average it out and do OK.
Plus, if you depend on free search engine listings only you becime extremely vulnerable to Google's whims, and if you read much on this subject, Google's been just bad these last few months. One day you're in the first page and the next day you're not even in the top 100 -
literally, that's really happening. Don't ever rely on just one thing.
Finally, one of the best things about AdWords is that you have complete control and you can test ideas before you roll them out. That's a great advantage which is not possible with free search engine traffic.