You love buying your shirts when they go on sale. And who can resist a buy-one-get-one-free offer? So when our stocks go on sale, why do we bemoan their low prices?

Smart investors such as Warren Buffett or Marty Whitman love it when their stocks are suddenly selling at bargain-basement prices. For them, these companies become no-brainer buys.

The investors who populate the Motley Fool CAPS community also like a bargain, apparently. Below, you'll find five stocks whose shares are selling at least 50% below their 52-week highs but that still earn top five-star honors from our investor-intelligence database. Consider it a BOGO sale on stocks.

Stock

CAPS Rating (Out of five)

% Off 52-Week High

Bucyrus International (NASDAQ:BUCY)

*****

55%

Nabors Industries (NYSE:NBR)

*****

53%

Pharmaceutical Product Development (NASDAQ:PPDI)

*****

56%

Terex (NYSE:TEX)

*****

72%

Valero (NYSE:VLO)

*****

51%


Naturally, we want you to look a bit more closely at these stocks before buying. You can get low-priced appliances in the dent-and-ding section of your home-remodeling superstore, but their quality might not be so good. Same thing here: Make sure there's nothing seriously wrong with the company before you plug it in to your portfolio.

Take two; they're small
Even though oil is hovering between $60 and $70, downstream oil operators are feeling the pinch of excess supply and weak demand. Valero is black and blue from the tweaking it took from the convergence of pricing for heavy and light grades of crude oil. Its latest earnings report looked as if it went a round or two with Mike Tyson after reporting a per-share loss of $0.48. The oil refiner is staggering around punch-drunk for the third quarter, with more losses expected.

Valero misjudged the pricing action of the lower grades, and margins have suffered as a result. Analysts contend that demand in the U.S. is the weakest of any major economy. Valero and ConocoPhillips (NYSE:COP) -- both of which rely heavily on domestic refining operations -- are struggling as a result. A new contract from the Pentagon won't appreciably strengthen margins, but at $230.5 million, it ought to at least help with Valero's cash flow situation.

CAPS member schapekop thinks that crack spreads, or the difference in price between crude oil and the petroleum products extracted from it -- such as gasoline -- will eventually get better: "Valero seems to be quite undervalued at present when looking at its net worth. As the economy will be turning sooner or later [crack] spreads will surely improve, since added capacity will cost heaps of money and cannot compete -- [Valero] will soar again."

Dragging through the muck
Producing draglines that can swallow small villages in a single scoop has been Bucyrus International's forte. These single-bucket excavators have capacities larger than 150 cubic yards. But with a global economic downturn causing mining companies to cut back operations, Bucyrus has seen its new order volume plummet. The dollar value of such orders fell by 83% in the second quarter.

That news has some analysts concerned about 2010 and beyond, but Goldman Sachs has no such concerns. It thinks coal demand in China will be a boon to both Bucyrus and rival Joy Global (NASDAQ:JOYG). That country's sharp recovery from the recession might be enough to spur demand all on its own. Industrial production in China rose 10.8% in July, while the economy expanded at a 7.9% clip in the second quarter.

It was the potential for improvements in emerging markets that led CAPS member MCCracker1 to rate Bucyrus last month as a market outperformer: "BUCY will be driven by emerging market demand and commodities exploration. Revenue ramping, small float, 75% held by institutions. Little downside risk at $20."

Have half a mind
It pays to start your own research on these stocks on Motley Fool CAPS. Read a company's financial reports, scrutinize key data and charts, and examine the comments your fellow investors have made -- all from a stock's CAPS page.

Sign up today for the completely free service, and tell us whether these stocks are twice as good at half the price.

Pharmaceutical Product Development is a Motley Fool Stock Advisor recommendation. Try any of our Foolish newsletter services free for 30 days.

Fool contributor Rich Duprey has no financial position in any of the stocks mentioned in this article. You can see his holdings. Test-drive The Motley Fool's full-size disclosure policy.