You'll get better prices if you look off amazon at one of the used book metasearch engines, like used.addall.com. You're also far more likely to end up ordering from a small, local store. To save on postage, you might order from one near you (or even pick up the book.)

Well that last one will only happen in France, after this. In the US you go to Amazon for the free postage. And since so many people go to Amazon for the free postage, they can somehow charge a higher price without postage than indie booksellers including postage. It's a brand premium, not a convenience or cost premium. Too many people have the habit of checking Amazon first.