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 like 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 companies whose shares are selling at least 50% below their 52-week highs but that still earn top honors from our investor-intelligence database. Consider it a BOGO sale on stocks.

Stock

CAPS Rating

% Off 52-Week High

Agrium (NASDAQ:AGU)

*****

56%

Constellation Energy (NYSE:CEG)

*****

71%

Flowserve (NYSE:FLS)

*****

51%

Harsco (NYSE:HSC)

*****

55%

Immucor (NASDAQ:BLUD)

*****

58%

Naturally, we want you to look a bit closer 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 into your portfolio.

Take two; they're small
The strong quarterly earnings report by pump and valve maker Flowserve has left everyone cautiously optimistic that this is a megatrend not to be missed. From the U.S. to China, Mexico to Bombay, governments are investing in their infrastructures on the basis of need and as a means of spending their way out of the recession. Look for other infrastructure companies, such as ITT (NYSE:ITT) and Mueller Water (NYSE:MWA), to get into the flow of things, too.

Yet before we allow ourselves to get too caught up in the wave of euphoria, let's remember that Flowserve also said backlog fell 20% from the year-ago quarter (even if it started to trend up in March), and that the trickle-down impact of government largesse takes a while to register. Indeed, the nonpartisan Congressional Budget Office has suggested that it will be years before the effects of the majority of the proposed stimulus spending is ever felt.

Flowserve, however, has a diversified line of business that should minimize the influence of the recession on its business. It acquired Swiss water-desalinization equipment maker Calder recently, to take advantage of the growing demand for increased urbanization and population growth.

CAPS member DepthMigration thinks its industry-leading position and diversification mean Flowserve could grow rapidly:

[Flowserve] is an industry leader in pumps and valves. Historically, they have concentrated on the [oil and gas] segment, but have diversified successfully and rapidly. I expect them to target what will be a huge, expanding market -- water. Very sensible balance sheet with plenty of free cash flow.

Bloody good
Standard practice among value investors is to look among the carnage of companies struck down by some isolated event. They probe for stocks that still have a future but are temporarily facing setbacks that have caused their values to decline dramatically.

That's probably the reasoning behind CAPS member 1269530085's suggestion that investors might want to give Immucor, a blood typing reagent maker, a second look after the Justice Department launched an antitrust investigation against it, causing shares to fall 25%. Says our CAPS member: "Too big of a hit from DOJ investigation. Strong economic profitability (EVA) … consistent cash flows, good industrial footprint."

But it's also probably worth noting that it would be wise to let the dust settle first before rushing in. Fannie Mae's accounting scandal a few years ago is a good lesson to follow. Even after it seemed that all of the bad news had come out, additional accounting irregularities surfaced to deal the stock a new blow -- and all before the mortgage crisis hit!

You might not catch the bottom by waiting, but you won't cut your hands by grabbing for the falling knife.

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.

ITT is a Motley Fool Inside Value recommendation. The Fool owns shares of and options on Flowserve. Try any of our Foolish newsletter services free for 30 days.

Fool contributor Rich Duprey also owns shares and options on Flowserve, but he has no financial position in any of the other stocks mentioned in this article. You can see his holdings. Test drive the Motley Fool's full-size disclosure policy.