Google AdWords

It is often not profitable for a single book push. Doing good old SEO is much better and will keep your book listed in the top 10 of Google for quite some time depending on the competition. Some of the easiest ways to do that are listed on the Marketing Your Writing Online page.

However, you can set your ad words limit to whatever you are willing to spend. I know one person that does $40 per month for their books. You could do $10 a month for 12 months and see if you get any results - that would be a pretty good $120 experiment.

I do a bit of adwords work for my job, not book related. But I would say that unless you have experience/knowledge of SEO, it's not worth it. If you're familiar with the stuff, it might be worth it. Maybe. It's pretty iffy for a specific book, because odds are people are not googling for a book. If they want a book, they'll go to amazon. If you have some very specific issues in your book that are unique, and think people googling about those items would be interested enough... that might work.

I target Australia and NZ only with my adwords (since those are the only countries where people can buy my books for now.)

Last year I spent around $600 on bookmarks, and while they're effective at giving someone a tangible link with the novel, I think hitting adwords for 2 weeks before launch and 4-6 weeks afterwards (ie. while the books are actually in the shops) would be a good move.

I'm planning on putting a bit of my own cash into this, since there will be four of my series novels in the shops, and it's time to give things a push.