Adwords is pretty cool but it does take a big time investment, or at least it did for me. There is a lot you need to learn before placing that first ad or that $100 will be gone instantly. if your careful, it can last a good long time.
If your ads are exactly what Google wants, you get a great rate, the less Google likes them, the more expensive they become. And it can be a real challenge to understand exactly what G wants from you.
Once I get into something, i tend to do it to the exclusion of everything else. So I probably spent WAY more time messing with it then I needed to. But if I had that time to spend over again, I would just spend it doing more SEO for my site.
