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

Stock

CAPS Rating (out of 5)

% Off 52-Week High

Celera (NYSE:CRA)

*****

60%

Compton Petroleum (NYSE:CMZ)

*****

81%

KV Pharmaceutical (NYSE:KV-A)

*****

87%

Pain Therapeutics (NASDAQ:PTIE)

*****

51%

Spartan Motors (NASDAQ:SPAR)

*****

56%

We want you to look a bit closer at these stocks before buying them. 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
Pain Therapeutics has known happier days, but still has the financial wherewithal to work through a downturn. In the meantime, investors are left waiting for King Pharmaceuticals (NYSE:KG) to resubmit its application for its joint, abuse-resistant formulation of OxyContin, called Remoxy.

Using a thick suspension technology licensed from Durect (NASDAQ:DRRX), Remoxy thwarts the ability of addicts to grind up the pills, a process that releases the drug and leads to abuse. King Pharmaceuticals just received FDA approval for another abuse-resistant pain medication, Embeda, using the same technology. King Pharmaceuticals plans on resubmitting its Remoxy application next year and recently signed a long-term supply agreement with Durect for the abuse-resistance technology. While that suggests King Pharmaceuticals is hopeful, there are more hurdles beyond approval from the Food and Drug Administration.

What's happening with Purdue Pharma? The original maker of OxyContin pleaded guilty several years ago to a felony charge of misrepresenting the difficulty associated with extracting the oxycodone from its time-release formulation. Now it's also racing to bring to market an abuse-resistant version that minimizes the amount of drug released when crushed or chewed and causes it to turn into a gel when mixed with liquid. It received the support of an advisory panel whose advice the FDA usually, but not always, follows.

Purdue Pharma says it could replace 90% of the current inventory of OxyContin within two weeks if it gets approval, a development that no doubt worries Pain Therapeutics' shareholders. Purdue Pharma realizes $1 billion in annual sales right now, and King Pharmaceuticals might have grabbed a sizeable share with its formulation. That would pay a king's ransom to Pain Therapeutics because its agreement with King Pharmaceuticals calls for a 15% royalty on the first $1 billion in sales, with a 20% royalty after that.

If the company can get its formulation to market, CAPS member FinanceGuy58 thinks Pain Therapeutics' lean operations spell trouble for the competition.

A virtual pharma development company with several shots on goal. Remoxy already partnered with King Pharma. Abuse resistant forms of oxycontin should be a big hit. Great royalty rates. Another pic, Durect provides the drug delivery system for one of their pipeline products. PTIE holds tons of cash too-not going away. Very lean company, they outsource almost everything.

With a market cap of $209 million, Pain Therapeutics is essentially trading for the cash it has in the bank, with no long-term debt on its balance sheet. The problem is there's no catalyst for further growth until Remoxy wins approval. If the drug is delayed or doesn't gain FDA backing, which might lead to the partnership with King Pharmaceuticals coming apart, things would be bad for Pain Therapeutics.

Have half a mind
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Fool contributor Rich Duprey does not have a financial position in any of the stocks mentioned in this article. You can see his holdings. The Motley Fool has a disclosure policy.