It's been a good year for stocks in general, but especially for small-cap stocks.

In the first 10 months of 2013, small-cap growth stock mutual funds produced an average return of 33.1 percent, compared with 26.3 percent for large-cap growth funds, according to Morningstar data.

While those returns are good, many say it's getting hard to find stocks that are priced well.

Editor’s Note: 5 Reasons Stocks Will Collapse . . .

"You say to yourself, 'How much better does it get?'" Michael Balkin, co-manager of the William Blair Small Cap Growth fund, tells The Wall Street Journal.

For some, the answer is not much. More stocks have "eye-popping" valuations than they did six months ago, Aram Green, co-manager of the ClearBridge Small Cap Growth fund, tells The Journal.

JB Taylor, manager of the Wasatch Small Cap Growth fund, is concerned about valuations too. "It wouldn't take much of a break in this overall market to really let the air out of some of the valuations," he explains.

But not everyone is bearish.

"We've got a very low-interest-rate environment, . . . and people are doing anything they can to generate returns, and historically the best place to find returns has been in small caps," Balkin notes.

In the big picture, "small caps are where you find the next Apple, the next Tesla Motors," writes Roben Farzad of Bloomberg Businessweek.

"Buy a big enough basket of them, and you're bound to end up owning a piece of the next big thing. The trade-off: the interim volatility of small caps is demonstrably higher than that of low-growth, established blue chips, and they get hit harder when the broader market freaks out as it did in 2008."

Editor’s Note: 5 Reasons Stocks Will Collapse . . .

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