Let's take the Resale Rights idea, and add another a twist: allow people who buy the ebook to change the affiliate inks you've included to their own.
This is generally known as rebranding, although that's a misnomer – the ebook will still carry your name, your content and your design (i.e., your brand) – it can be a powerful technique.
You need special PDF rebranding software which will enable you to provide your customers with a version of the ebook in which the links can be changed, by means of a small accompanying application that you bundle together with it. Take a look at Instant PDF Profits or Viral PDF
Marketing Your Rebrandable Ebook
You can add an additional charge to the purchase price of your ebook for the right to modify the affiliate links within it. So, for example, you could set the base price of your ebook at say $27, and then charge $37 for resale rights, and then $47 for resale and rebranding rights.
Another way to use rebranding is to simply give your ebook away for free, and allow everyone who receives the ebook to change the affiliate links to their own (possibly for a small fee) and give the book away to others.
This creates a viral marketing effect, with your ebook spreading far further than it would have done by any other means.
That's because when you give people the ability to put their own links into the ebook, it creates a huge incentive for them to give away as many copies as they can to make money for themselves.
All you need to do is reserve a couple of links in the ebook for your own sites and products (quite natural since you're the author), or perhaps a good recurring income affiliate program, and you're set to make a killing.
If you have other products of your own, another option is use PLR content to create an ebook that relates to one or more of them. Include links to your products inside the ebook and make it available to current and potential affiliates to rebrand and give away as a lead generator.