This is like asking, "how much would you pay for a 180-page book?" What's the book about? What's the writing like? What's the genre? What's your primary demographic?
Show me samples from the book and give me a synopsis, and then maybe I'll give you a better estimate.
I'm not talking about a specific book. I just mean if you flipped through it and liked the art and you read the back and thought it was a good storyline how much would you pay for it? There are certain limits I would have no matter how good the story or the art was.. So I'm just curious how much people would pay for something they like.