CafePress whiffed badly on book pricing. The base fee is five bucks per book for saddle stitch or wirebound, and six bucks per book for perfect bound. On top of that, they’re charging six cents per page, and that’s printed page rather than physical page.
A 250 page paperback would have a base cost of $21. A 32 page comic book would have a base cost of $6.60. (Er. $6.92. I dunno where I went wrong.) Profit margins are optional. I don’t think this’ll take off.
Addendum: it’s not actually so bad for RPG books. Note that you could print that 250 page paperback in 8.5×11 format, retail it at $25, and make four bucks a book. But RPG books are a small market form.
Another addendum: those prices dropped quick. Now your $25 RPG has a profit margin of around 10 bucks.