When Jeff Bezos announced to his Amazon staff his concept for the Amazon Marketplace in November 2000, many people — inside and outside Amazon — thought he was crazy. Amazon was inviting in other sellers — individuals and merchants — to compete against Amazon’s owned inventory on Amazon.com.  As full price merchants were added in categories such as consumer electronics, apparel, and baby products in the early 2000s, the head shaking continued. To paraphrase, Jeff Bezos claimed this was about “the world of perfect information.” Customers are going to find the lowest price online if they really want to, and they should be trained to find it on Amazon. Maybe Amazon could grab a piece of the pie along the way.

Of course, what was once seen as crazy is now viewed with envy, as the marketplace now represents approximately 35% of Amazon’s revenues and 30% of total units sold in Q4 2010.* Amazon charges anywhere from a 5% to a 25% revenue share on a sale through its marketplace, roughly determined by dividing the expected margins in a category in half — to be shared with the merchant. With only limited incremental technology and category management costs, the profitability of this for Amazon is easy to see. And as a result, it has also solidified Amazon’s role as the leading product search site. This success is already breeding imitators in Buy.com, Sears, Walmart, NewEgg, and soon a whole host of large UK retailers. And let’s not ignore Apple’s iTunes, clearly a very successful marketplace, though of a somewhat different flavor.