The new amazon widget

Christina Wodtke at elegantHack takes a look at this Amazon Widget, which has a clumsy interaction design. Seems Amazon is still testing it. I don't know how expensive (or inexpensive) it is to actually test designs on a live site. Macromedia did it sometime back with their new site design and Amazon apparently uses quantitative techniques to do their testing. Is this the right way to go about it? Because it seems some of the mistakes in these designs could have been caught much more easily in a lab. Maybe usability labs actually cost more than putting the site on live and then getting feedback...