The United States Postal Service boosted their rates pretty high recently. I kept the shipping prices as low as I possibly could, and I know it's still pretty high. But two giant omnibuses are gonna be heavy, and that's costly.
Other comic book kickstarters have ended up *costing* their creators money once they get to the shipping part! They ended up with less money than they had before the kickstarter. I'm not in a position to do that.