Unfortunately, one eBook edition to go to all vendors is not a good solution if you intend on placing buy links in the back matter. (bbebooksthailand.com)
Keep your books, with buy links, prominently visible on your blog pages, just don't try to sell them directly. (rmfw.org)
If there's an explicit mention of buying links or anything that suggests the agency pays for links, run away. (entrepreneur.com)