I think that with e-junkie there is no need for aweber.(not for delivery of the book.)
e-junkie takes care of the whole delivery if your ebook. You just need to have a PayPal acct. And it can be a free acct.
As far as I understand (I'm new too
aweber is used as an autoresponder. When you are building a list, or sending a series of marketing emails to prospects. I don't think you NEED (correct me if I'm wrong, anyone)aweber to just distribute your ebook.
Good luck with the ebook!