Is A $25 Discount Worth Seeing Ads On A Kindle?

It seems as though ever since Amazon first started selling the Kindle there has been speculation about how the company might come up with ways to make the device affordable if not free. One idea that I heard is that Amazon would create a monthly book club were you commit to buying a certain number of books per month, which subsidized a discount on the Kindle. Another idea is that Amazon would provide free, or heavily discounted, Kindles to Amazon Prime subscribers.