OK folks, I'm not much of a hacker, but this is how I usually try to grab paid products for free.
If I'm not after a particular product but I'm doing some time pass, I'll go to google and search for "thank you for your order" + clickbank OR "download page" + clickbank OR "your credit card has been charged" + clickbank
.. etc
Now if I want a particular product, I first search google by site

roductwebsite.com
I use filters as required (so if there's a blog with /blog/page.html or whatever) I'll search for site

roductwebsite.com -blog. If there are lot of results and I want only pdf files, I'll search for site

roductwebsite.com filetype

df
If its not indexed and I want it badly, I'll try combinations like thankyou.html, download.html (and also the .htm extensions).
If it has a paypal button, I'll view the source of the page and search for "return". This only works if the website owner uses the normal paypal buttons and not the encrypted buttons.
Last (but definitely not the least), I'll check out archive.org.
Simply visit web.archive.org/web/*/productwebsite.com/*
Just replace productwebsite.com with the domain you want.
That's all, folks! If I give you a fish, you'll eat for a day. But if I teach you to fish, you'll eat for a lifetime! I also have some "fishes" which I'll post later.
enjoy!