Dotsie,
I don't know what all you have going, but have you tried the Associate program at Amazon? You can earn up to 10% referral fees and all you have to do is show books on a web page with a link to the Amazon page. Since so many of the people here (BWS) have books, maybe they would really support your marketplace connection to Amazon.
http://www.amazon.com/gp/browse.html/104-2009826-4403908?node=3435371

I'm not sure about now, but last year it was set up so that if a customer clicked into Amazon through your site, you would get a referral fee for EVERYTHING they ordered when they ordered your referral product. That could be lucrative I would think.
Just a thought.....especially since you have so much traffic which is the key to success as an affiliate.
Dannye