Measured by price-to-sales, Amazon.com (AMZN 1.03%) stock is about four times as expensive as Wal-Mart. Price-to-book? Same thing. The stock is expensive -- there's no way around it. But it carries a premium for good reason. Besides the company's commonly cited massive e-commerce opportunity, Amazon faces two additional opportunities investors shouldn't overlook: Amazon Prime and AmazonFresh.

Amazon Prime
For $79 a year, Amazon members can lock in free two-day shipping on millions of items, plus some free access to instant streaming of thousands of movies and TV shows. Current members are well aware of the service's usefulness. Blogger Jason Calacanis went as far as to say: "There are two types of people in the world: those with Amazon Prime and those without. ... And to be clear, Prime is a cult you will be joining." This might sound like a rash statement to the uninitiated, but current members might not bat an eyelash at this blogger's enthusiasm. 


Source: Amazon.com.

"Once shoppers are in, they're hooked," says Fool contributor Demitrios Kalogeropoulos. It didn't take long for Amazon Prime to gain traction. Just six years after it debuted, in 2010, Bloomberg Businessweek's Brand Stone said that, "Amazon Prime may be the most ingenious and effective customer loyalty program in all of e-commerce, if not retail in general."

Amazon Prime induces higher customer engagement; members spend heavily, doubling the spending of non-members. And the service is addictive; in a 2011 survey by Piper Jaffray, 92% of current Prime members planned to renew their membership.

Morningstar's Hottovy has pegged Amazon's current Prime members at 10 million. He expects that number to grow to a whopping 25 million by 2017.

AmazonFresh
With just one move, Amazon sent its addressable market skyrocketing. The introduction of Amazon Fresh, an online grocery business that promises same-day and early-morning delivery on orders of $35 or more, introduces Amazon to an $850 billion market (based on personal consumption expenditures data from the Bureau of Economic Analysis) -- and that's just in the U.S.


Source: Amazon.com.

Amazon seems to be working hard to make good on plans to expand its grocery business. Earlier this month, Reuters reported that Amazon would soon introduce AmazonFresh to Los Angeles and the San Francisco Bay area. And now, the AmazonFresh website is reporting that AmazonFresh has become available in the Los Angeles area.

Piggybacking on the success of Amazon Prime, Amazon is rolling out the Fresh service as a membership, costing $299. This includes the Amazon Prime benefits.

Disruption at its best
Amazon stock may be expensive, but disruptive moves like AmazonFresh and continued adoption of Amazon Prime could drive considerable growth for years to come. Despite the stock's premium, the majority of Motley Fool Caps all-star players believe Amazon stock will continue to outperform.