Re gathering keywords, have you tried targeting the people advertising on your book pages? Anything that looks like a match, but without clicking on them of course (I know you don't). That's partly why I wrote this new tool, so I can get the asin/store page from the sponsored link without clicking it.
Have you ever set up ads with ASINs? I like them because they're targeted to that one book, but I think they're harder to get going somehow.
On a related note, it's not clear to me whether having a bunch of different, conflicting ads for the same book is a major disadvantage. For example, if I have a bunch of AMS ads for the same book, including...
1 categories ad (e.g. Humourous Science Fiction)
1 keywords ad (book titles - e.g. Hitchhiker's Guide)
1 asin ad (specific asins (some ASIN for HHG)
1 keywords ad (author names - e.g. Douglas Adams)
1 search terms ad ('science fiction humor' for example)
1 keywords ad (broader terms like Douglas Adams Books)
Now, one product on amazon will match all those at once, so which of my ads does AMS show there? The one with the highest bid? Or does it pick the first matching ad of mine, which might have the lowest bid of the lot, not even checking the other ads?
The only way to be sure would be to turn off all conflicting ads, but I don't want to do that because chances are they'll never fire up again.