What you say can be accurate up to a degree because beside Google, the other advertising programs may not reach out to such a large group of audience over the net and since there are usually fewer networks and portals that actually publish the ads, so not a lot of clicks might be expected, especially if you look for ways to improve targeted traffic to your website. Instead of looking for some huge systems and millions of impressions, you may be better off using smaller packages.

You know, search the net to find some forums, blogs and directories that are highly relevant to your web niche and the selected field, then check out if any of them is selling advertising spots and place your ads on them. This way, you will be using affordable programs compared with most PPC networks and at the same time your ads will be in front of people who are looking for relevant materials, information and products which your website is trying to offer to them.

The amount of clicks is not an issue, I am looking more for high quality. I have used bid4keywords which is ok so far but nothig great.