Where I work, we have a publishing operation and they ship quite a few things out of there. You'd be surprised how expensive shipping is, especially on these larger items. And you can ship to one area and it seems cheap, and the next area it seems insanely expensive (both receiving the same item). I don't know the logic the carriers use, but they somehow figure up costs by the location and it varies, a lot sometimes.
Shipping just went up this year too, across the board. USPS was pretty darn affordable for the longest time, and this year they jacked their rates like 25%. It's nuts. Shipping is a killer right now for anyone, worse than I've seen for a long time.