Tokki, it’s both. I want sales and also want to get the right also boughts.
So youre saying if I confine my keywords to the names of the top sellers in my genre, I WON’T get that many sales? I assumed if I bid very high for these keywords, then my ad would appear on the first page of their also boughts and that would mean so much visibility that sales would take off.
If you're looking just for visibility, you want to aim for low cost per click, because your budget will go further.
if you bid high and aim for the bestsellers in your category, you'll burn your budget out really fast, and get very little visibility.
I'd advise aiming for just one tier higher to wherever you are, and not the bestsellers. For example, if you're a small fish, go for the smallest of the medium fish in your genre. You'll get more views because Zon will consider you more relevant, and you'll get lower-cost clicks, which means more clicks before your budget burns out. For reference, I usually only have a couple hundred search terms on this kind of ad, and I prefer new releases, as they are hotter movers and get more traffic.
If you're not the smallest of fish, you can also aim for lower tiers because you're likely to dominate their alsoboughts, while getting low-cost clicks.
I own KDP Rocket, and it has its utility, but it aims for the top (most expensive) terms. Also, lots of other people are using that product the same way, driving the cost-per-click on those top terms even higher. Rocket will also return non-relevant terms, so you'll have to weed those out. The good news is that you can get better results for this particular purpose by doing your own legwork without buying any programs. Look at the alsoboughts of your books, and the alsoboughts of your alsoboughts. Look for the titles and authors that are just one tier up from you. That's where you'll find your most advantageous search terms for visibility/cost per click.
If, however, you're looking to influence alsoboughts, this is a different AMS strategy. You'll want a very small list of terms with very high bids, and you'll pay a lot of money for not many sales. KDP Rocket is great for this, but you can also dig up the data yourself via the bestseller charts. This strategy is most effective when your book is new, before you've had many sales. The end game here is not the direct sales you make, but the tangential sales due to your alsoboughts. This is generally a high-roller strategy, for people who have marketing budget to burn.