You are correct on watching the conversion rates, and more importantly when buying an airline ticket the currency choice is paramount. (nomadicchick.com)
One of the few good benefits with buying your airline ticket with your rewards points, is that you will actually earn the airline miles when you fly. (thepointsguide.com)
When selecting the upgraded shipping speeds it's like buying an airline ticket for your books and can get quite expensive. (diggypod.com)