NEW YORK (CNN/Money) - After all that's happened, you can't say investors aren't wiser now than they were when the Dow Jones industrial average pushed to first close above 10,000 more than four years ago.

With the index once again marching toward the 10k mark, valuations, no matter how you stack them, are cheaper now than they were when former Big Board headman Dick Grasso frisbeed those Dow 10,000 hats across the exchange's floor on March 29, 1999.

The Dow trades at about 19 times the past year's earnings compared with its March 1999 P/E of 25. Back then, the broader S&P 500's P/E was about 29; now it's at around 21. Use any of the other earnings measures Wall Street likes to use -- earnings under generally accepted accounting principles, trend earnings, forward earnings and what have you -- and the song remains the same: Stocks are much cheaper now.

But just as wiser doesn't necessarily mean wise, bears argue that cheaper doesn't necessarily mean cheap. Cliff Asness, managing principal at the hedge fund AQR Capital Management, recently sent a series of haiku to his investors, one of which complained:

Best they can argue
Not as high as ninety nine
Faint praise is damning

To figure out valuations, Asness looks at how the S&P trades relative to average annual earnings, adjusted for inflation, over the past 10 years. On that basis, the S&P's P/E is around 26. That's lower than its March 1999 level of 42, but it's also well above the historical average of 14 to 15.

Asness believes that stocks have historically been a bargain -- a P/E of 20 or so, the way he looks at it, seems about right to him now. But he also thinks that P/Es are going to have to dip down to historic levels for a real bull market to start. For that to happen, the S&P would have to drop by 40 percent. Or earnings would have to accelerate a great deal. Or a little of both.

Another way of looking at valuations, put forth by Warren Buffett, is to compare the total value of U.S. public companies with Gross National Product. Something akin to a price-to-sales ratio, if you think of it.

Currently, U.S. market capitalization looks to be about 131 percent of GNP. That's nothing like the 176 percent logged when the Dow first crossed 10,000. But prior to 1997, it was never as high as it is now. It's no wonder that Buffett is so dour about the stock market.

One valuation method argues that stocks are quite cheap, however. According to the so-called Fed valuation model, which looks at the relationship between the S&P's price-to-earnings ratio, based on analysts' expected earnings, and the 10-year Treasury note, the S&P looks like it is about 30 percent below where it should be. In March 1999 it was 30 percent too rich.

People see more flaws in the Fed model than are worth enumerating. For now we'll stick to pointing out that it doesn't say anything about absolute stock market valuations, just stock market valuations relative to Treasury prices. It's sort of like saying that, in comparison to "Gigli," "Ishtar" isn't such a bad movie.

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"Saying that stocks are cheap relative to an asset class that itself is really expensive -- that's a fragile comfort," said Doug Cliggott, who heads up U.S. research for the hedge fund Brummer & Partners. "To me the risk profile of the market in some ways is even higher than back in 1999. Back then people were buying because there was tremendous enthusiasm for stocks. Now they're buying them because they're turned off by the alternatives."