hstraf, why don't you just use a conventional "buy it now" button linked to paypal's IPN system, so you could have a PHP script using the IPN payment API to send them an email when payment is confirmed with the URL to the ebook (or you could potentially attach the ebook to the email). Hope that's helpful
Doesn't Paypal let you redirect to a "thank you" page after someone purchases with a "buy now" button? Why not just include the link there with instructions to download the book, and you could change the location of the book every so often if you're concerned about theft.
Otherwise - maybe something like clickbank would help here?
He doesn't want to learn PHP, etc... and I don't have time/effort to code it for him.
All you would need to do is take the default IPN script and literally add a PHP statement to send an email to the address of the purchaser, PayPal makes it so easy they even provide the PHP/ASP/CFN/JSP/Whatever script to verify the payment went through and instruct the site in question to carry out an action... surely using the php mail command isn't too much effort for you?