Something else to keep in mind about Clickbank (you may already know this)...
Some of the products are used by their creators merely as front-ends into higher-priced stuff. For example, you might see a book or piece of software priced at $27 with a 75% commission. The high commission (percentage wise, at least) motivates a ton of affiliates to play. Everyone mails their lists to drive traffic and sales. Assuming the refund rate is reasonable, affiliates are happy. They continue to promote the product.
Meanwhile, the product creator is happy to pay 75% commission to affiliates because he/she is gathering a targeted list of buyers. Those buyers go onto a list. The product creator mails this list to move these leads into higher-priced niche products or memberships (continuity programs). From $27 to $67 to $97 to $397, etc.
A lot of folks at WF look down at CB, but there are smart ways to use it. If you're trying to make a killing with one ebook, you're fighting an uphill battle. It can be done, but you'd need to get the big guns to "product launch" it for you. I'm not talking just mailing their lists. I'm talking forum work, blogs, affiliate contests, free reports, "leaked" reports, special interviews, launch date, server downtime, etc.
It's a system.