Ping to an idea......
Yes, you can do this. I've done this with my software dialer.
What you do is set up a webpage, like this: http://www.gegaccess.net/search.html
you set up an action at ebay advertising this page. As they check out through paypal, the paypal cgis them to the page for the software, ebook, anything to download.
These instructions are at paypal ;)
You ebook would download the same as my dialer :)
Good luck to you :D