So let me see if I understand.
For each book I promote I would create a seperate redirect page (20 books = 20 redirect pages) and put them in a folder named "books". Then wherever in the site I referenced that book and wanted people to go to the merchant page, the status bar would show:
"sitename.com/books/bookname.php"?
And let's say that I was tweeting the review of that book, I could either have people go to the review using "sitename.com/postnumber/postname" or right to the book on the merchant site by using "sitename.com/books/bookname.php"
Am I getting it?