The differences are often significant: "Lehninger Principles of Biochemistry, Third Edition," for example, lists for $146.15 on the American Amazon site, but can be had for $63.48, plus $8.05 shipping, from the British one. And "Linear System Theory and Design, Third Edition" is $110 in the United States, but $41.76, or $49.81 with shipping, in Britain. y college bookstores, meanwhile, have taken matters into their own hands, arranging their own overseas purchases.