I'm always looking for a good deal, whether that means buying an extra box of Golden Grahams when they're on sale, or pouncing on undervalued stocks. The idea that anybody would sell a stock for less than its worth may seem silly, but legendary value investor Ben Graham (no relation to the cereal) tells us, by way of allegory, how we can look out for these situations.

In The Intelligent Investor, Graham introduces readers to a wacky chap named Mr. Market. He drops by your doorstep on a daily basis, offering to sell you interests in businesses he owns, or to buy from you interests in businesses you own. Sometimes Mr. Market will show up at your door very excited, offering you premium prices for your holdings; at other times he'll be inconsolably depressed about the future, willing to sell you what he has for as low as pennies on the dollar.

To find some of the stocks that Mr. Market is depressed about, I've turned once again to The Motley Fool's CAPS investor community. Each of the companies below had earned a five-star rating (the highest) by our community of investors just 30 days ago:

Stock

30-day return

One-year return

Current CAPS rating

Quicksilver Resources (NYSE:KWK)

(56.2%)

(57.4%)

****

Southern Copper (NYSE:PCU)

(53.9%)

(70.3%)

*****

Joy Global (NASDAQ:JOYG)

(51.2%)

(48%)

*****

CapitalSource (NYSE:CSE)

(46%)

(51.2%)

*****

Johnson Controls (NYSE:JCI)

(44.6%)

(52.7%)

****

Canadian Natural Resources

(44.5%)

(39.2%)

*****

Focus Media Holding (NASDAQ:FMCN)

(43.8%)

(68.2%)

*****

Data from Motley Fool CAPS as of Oct. 21.

As the table shows, these stocks are all still very well-regarded by the CAPS community, despite their underperformance over the past month. While these are not formal recommendations, they could be a great place to kick off some further research. I'll get you started with some thoughts on Southern Copper.

Why so blue?
Part of the reason is simple -- the entire market is blue. In fact, a stock that hasn't lost the same 20% the S&P has shed over the past month is a winner right now. But that doesn't tell us much about why Southern Copper has been chopped in half by that hatchet-wielding Mr. Market.

We should be getting third-quarter earnings from Southern Copper some time over the next couple weeks, but it's apparent that investors expect results to start falling hard. Net profit in the second quarter was down 25% from the prior year, but that still translated to $0.62 per share for that quarter alone. Over the past 12 months, the company has earned $2.32 per share, putting its trailing P/E ratio at just more than 5.

But results certainly could take a big hit. Copper prices have come to a screeching halt, falling roughly 45% since June. Freeport-McMoRan (NYSE:FCX), the Galactic Empire of the copper universe, also confirmed that the falling prices are causing pain when it reported third-quarter earnings down 30% from last year.

What the bulls say
On CAPS, Southern Copper bulls seem to be hoping that the current rock-bottom valuation will be some cushion, even if results do deteriorate. Gunnymarine cited the stock's low, low P/E ratio and hefty double-digit dividend as reasons to give it a hard look: "Below 30 its a steal, below 20 is highway robbery, at 12 dollars, you should go to prison. Get it while its hot, and let the dividends roll!!!!!"

Meanwhile, CAPS All-Star PaddingFool focused more on the demand side of the equation, recently noting:

At these levels the price suggests the use of copper has stopped. This isn't the case! Copper continues to be an important material and its continued use is guaranteed. China is still a huge user and the current price is a bargain for this company. And don't forget that dividend!

Do you think the recent drop has created a good buying opportunity? Or will copper and Southern Copper both continue to get smacked down like a Coney Island Whac-A-Mole? Let the community know what you think -- head over to CAPS and share your thoughts with the other 120,000-plus members currently posting their picks and pans. Even if you'd prefer to pass on Southern Copper, you can check out a few of the other stocks listed above, or any of the 5,400 stocks in the CAPS universe.

More CAPS Foolishness:

Focus Media Holding is a Motley Fool Global Gains and Rule Breakers pick. CapitalSource is an Income Investor selection. The Fool owns shares of CapitalSource. Try any of our Foolish newsletter services free for 30 days

Fool contributor Matt Koppenheffer does not own shares of any of the companies mentioned. You can check out what Matt likes in CAPS by visiting his CAPS portfolio. The Fool's disclosure policy knows how to drop a stock like it's hot, but only when the company is truly cold.