I only have Vol. 0. I'm ashamed.
Don't buy any more comics until you have read The Goon. Seriously, BLOWS Golly! out of the water (and I think that is a fabulous book). The Goon is a top ten all time title for me. It is AMAZING.
And what you really need to understand about 0 is that it isn't really scraps as much as it is really early work for him. Eventually he decided to create a storyline and his art is in a completely different place now than it was then.
I own like a total of 15 art prints, TWO of them are Goon prints by Powell.
Pull list: Afterlife with Archie, Bodies, Chilling Adventures of Sabrina, Coffin Hill, Dead Boy Detectives, The Fade Out, The Goon, Harley Quinn, Hinterkind, Iron Fist: The Living Weapon,The Maxx Maximized, Miracleman, Ms. Marvel, Multiversity, Rasputin, Rocket Raccoon, Sandman: Overture, Silver Surfer, The Walking Dead, Wonder Woman