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Investors interested in international plays should give serious consideration to Baidu stock at these prices. Photo: Rafael Matsunaga, via Wikimedia Commons.

Shareholders of Baidu (NASDAQ:BIDU) -- China's largest search engine -- have seen better summers. With the stock down roughly 40% since its January highs, some might consider bailing on the once-promising company. But I think investors should consider doing the exact opposite and buy more, as Baidu stock hasn't been this cheap in a long time.

In fact, the last time it was trading at such levels, it promptly jumped about 150% over the ensuing 13 months. There's no guarantee that it will happen again, but if you buy shares today, you get an even stronger company at just as good a price. Read below to find out what I mean.

Cheapest since 2013?
There are lots of ways to evaluate the affordability of a stock. The most popular is price-to-earnings (P/E). Over the past twelve months, Baidu has brought in $5.99 per share. That means at Wednesday's close of about $142, the stock was trading for roughly 24 times earnings.

That may sound like a lot, but this is a company that has seen its revenue climb by 46% per year over the last three years, while earnings have grown at a 15% clip (more on why earnings have grown slower below). Comparing it to years past, Baidu hasn't been this cheap since July 17, 2013.

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That corresponds to when Baidu chose to acquire 91 Wireless -- at that point China's largest app distributor. Investors had bid the stock down prior to that on concerns that Baidu wouldn't be able to transition successfully to a mobile platform.

The acquisition proved that management was serious about being a major mobile player. Two years later, mobile now contributes more than half of the company's revenue.

Cheapest since the Great Recession?
But perhaps a better way to measure Baidu is by its price-to-sales ratio. We are still in the early innings of the Internet revolution in China. While Internet penetration in the United States is already hovering near 85%, it's roughly half of that in China. There are literally hundreds of millions of Chinese consumers coming online -- many of them via mobile devices.

Instead of collecting profits now, founder and CEO Robin Li has been pouring revenue back into the business, first investing in a mobile platform and now focusing on new ventures (again, more on that below). The point is, earnings might not be the best proxy for measuring the long-term potential of Baidu.

If we look at the company's current price-to-sales ratio, it currently sits at about 5.5. The last time it was that low was January 14th, 2009 -- the depths of the Great Recession.

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For perspective, the stock traded for just $11 per share on that date. Even after the recent 40% sell-off, you would still be sitting on a 12-bagger if you bought at those levels.

Getting a better deal for your money
But there are some huge benefits to buying today, as opposed to 2009 or 2013 -- for one, you're getting a stronger company. Baidu has successfully made the transition to a mobile-first company, and Li is focusing on what he's calling the "Next Baidu."

This involves creating an extensive O2O network. That stands for "Online-to-Offline". In essence, he's trying to capitalize on an opportunity that his American counterpart -- Alphabet (NASDAQ:GOOG)(NASDAQ:GOOGL) -- was unable to.

When an American consumer wants to order a pizza, buy movie tickets, or schedule a vacation on their mobile device, they often use a company's app to get it done. Google usually has no part in the transaction.

Li, realizing he still has time to alter the way things are done in China, is trying to change that for Baidu. He's spending lots of money now to partner with local Chinese businesses to set up easy ways to connect consumers with companies. In the end, that would benefit Chinese business owners who are slow to adopt the Internet, and Baidu, which would take a cut of each transaction.

While the Chinese economy may enter a period of slower growth than in years past, I think it would be silly to assume the Internet adoption will slow at all. This is a force that's here to stay, and Baidu stands to benefit from it more than anyone else.

Eventually, the fear that's running through China will subside, and when it does, I believe we will see that Baidu's decision to forgo short-term profits in an effort to maintain long-term dominance will payoff handsomely for shareholders. That's why I bought shares a few weeks ago, and why I have no intentions of selling my shares anytime soon.

Brian Stoffel owns shares of Baidu, Google (A shares), and Google (C shares). The Motley Fool owns and recommends Baidu, Google (A shares), and Google (C shares). Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.