How does that go down? Do the buyers just send payment hoping the person will email or pm them the eBook? Is a link like e-junkie set up?
People use all kinds of ways, a lot people give them away or sell them really cheap as a way to market another service. On the forums it seems like most people just use there paypal account for payment and email the download link to someone when they pay.
to add to above, sometimes they make autodelivery where you are redirected to download page after payment or auto email respond wth donwload info or the ebook itself sent to you.