What is a good conversion rate for Amazon.com?
Unless you are comparing sites that are very much the same and sell the same items, comparing the conversion rates that Amazon reports doesn't mean much.
The conversion rate on your Associates reports varies widely based on the type of your site and how you interface to Amazon.com. For example, if you "pre-sell" the customer, the conversion rate reported will be higher than if you just provide a generic link to Amazon.com. If you use Amazon's "add-to-cart" interface your reported conversion rate will be much higher than if you provide text, banner, or "widget" links to Amazon pages.
And the conversion rate Amazon reports is misleading. Generally "conversion rate" is defined as the percentage of visitors to your site who place an order. Amazon, however, displays the ratio of the number of items ordered to the number of click-throughs.
For example, assume your site gets 100 clicks on two different days. One day, one visitor buys ten items. The next day two visitors buy a total of five items. Amazon will report a higher conversion rate for the first day when the rate was actually higher on the second day.
If your site sells inexpensive consumables that people tend to buy in quantity, Amazon's reported conversion rate will tend to be higher than for a site that's trying to sell expensive things like TVs.
Of course, the only statistic that really counts is the one that measures what you get out of your site. Is your goal to make money, build a community, support a cause, etc.? If it is to make money, the best statistic, of course, is how much money your site makes. :-)