$1 billion. $2.3 billion. $6 billion. (Hike!)

As the purported price tag for Groupon grows fatter than a turkey-stuffed American on a holiday weekend, Fools are beginning to wonder: "Is Google About to Make a $6 Billion Mistake?" Why, just yesterday, my Foolish colleague Rick Munarriz argues there's no need to buy Groupon. That Travelzoo (Nasdaq: TZOO),  OpenTable (Nasdaq: OPEN), AOL (NYSE: AOL), or Yahoo! (Nasdaq: YHOO) can easily duplicate the company's business model. That some of them are doing so -- and that Google (Nasdaq: GOOG) could, too. Many believe that Google paying $6 billion to buy Groupon is just plain insane.

I disagree.

A bargain's a bargain, no matter the price
Why? Because the numbers prove it: If Google can grab Groupon for $6 billion (or less), it'll be getting more than just a "daily deal." Google will score the deal of the decade.

Consider: As recently as a few days ago, most analysts on Wall Street were speculating that privately held Groupon did $500 million in business per year. At a total purchase price of $6 billion ($5.3 billion upfront, plus a $0.7 billion earn-out), Google would be paying 12 times revenues for that revenue stream. Not a screaming bargain, but not much more than it paid for DoubleClick in 2007, and a whole heckuvalot cheaper than the 150x sales multiple Google antied up for YouTube in 2006.

Crazy cheap
And it gets better. $500 million was the sales number analysts ascribed to Groupon last week. Already today, people close to the company are hinting that Groupon is bigger than we think. One figure now making the rounds: Groupon's annual revenue run-rate hit $1 billion in 2010, and is on track to leap 50% in 2011. If true, this suggests the P/S ratio of a $6 billion Groupon would drop to 6-times, or perhaps even lower, to 4x sales.

Now let's put those numbers in context. Google itself sells for 6.6x trailing sales, and 5.4x its projected revenues for next year, which are expected to grow 22%. In other words, Google appears to be buying a faster-growing company (50% versus 22%) -- and paying a lower sales multiple for it.

Better than a fruitcake
To top it all off, this would ensure Groupon won't turn up as an arm of Microsoft's (Nasdaq: MSFT) Bing search engine tomorrow. Nor will Amazon.com (Nasdaq: AMZN) get its grubby little hands on Groupon (which you know it would love to do, post-Woot!)

But Fools, that's all just icing. The valuation is the real cake here, and to me, it looks right tasty. Even at $6 billion.

Fool contributor Rich Smith owns shares of Google. The Motley Fool has a disclosure policy.

Google and Microsoft are Motley Fool Inside Value recommendations. Google and OpenTable are Motley Fool Rule Breakers picks. Amazon.com is a Motley Fool Stock Advisor choice. Motley Fool Options has recommended a diagonal call position on Microsoft. The Fool owns shares of Google, and Microsoft.

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