They have a RPG promotion this weekend. I ended up rebuying both Book 1 and Book 2 just to have a spot to always redownload them without looking for my cd key (Book 2) or emailing Basilisk (Book 1)
Edit: so where's the Book 3 preorder button on GoG?
Speaking of GOG...
Re: Speaking of GOG...
That would be "prepurchase" (like Guild Wars 2 did) not preorder