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 the stocks they favor are suddenly selling at bargain-basement prices. For them, these companies become no-brainer buys.

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

Stock

CAPS Rating (out of 5)

% Off 12-Month High

Alvarion (Nasdaq: ALVR)

*****

56%

ATP Oil & Gas (Nasdaq: ATPG)

*****

62%

Spectrum Pharmaceuticals (Nasdaq: SPPI)

*****

61%

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
It's hard to shake the notion that WiMAX equipment provider Alvarion hasn't seen the future -- and it doesn't include WiMAX. Instead, LTE -- short for "long-term evolution," the standard being backed by Verizon (NYSE: VZ) and AT&T -- seems to be wireless communications providers' future standard of choice. Growth is slowing, and management has chosen to lop off 20% of its workforce while switching to include a service model. With what looks to be a dying technology, it's understandable the stock has sold off.

But hold on. LTE technology is developing, but hasn't advanced enough to fully exorcise a few glitches of its own. And even its biggest proponents like Verizon are coming to LTE through a circuitous route, which first runs from Verizon's EVDO network, through CDMA, before accepting LTE. There's also the problem of spectrum allocation, a lack of handset availability using LTE, and perhaps most importantly, issues with providing voice over the network.

WiMAX, on the other hand, has WiMAX 2 coming out soon, with Intel (Nasdaq: INTC), Motorola (NYSE: MOT), and Samsung all committed to accelerating its development. While many major U.S. carriers have put their chips with LTE, that could come back to haunt them. Many experts consider video the biggest driver for mobile data traffic, accounting for 64% of mobile bandwidth by 2013. According to Intel, WiMax is the better solution to meet that demand.

Highly rated CAPS All-Star UltraLong thinks Alvarion will start growing in the latter part of the year, as orders pick up:

Despite delayed customer orders in the early part of 2010, I see stronger demand in the second half of this year and I see a larger suitor making a play at Alvarion if it remains this significantly below book value. Notice I haven't even mentioned how ridiculously low it is on an RSI perspective making this also a great technical entry point. There's really no reason ALVR should be trading below $4 or accept a buyout for any less than $6.

Holding the trump card
With "top hat 2" in place, BP (NYSE: BP) is finally getting a handle on the disaster it created in the Gulf of Mexico. Oil's still gushing out all over the place, but at least it looks as though a lot of the crude is finally being captured.

Yet the moratorium on offshore drilling imposed in the wake of this environmental catastrophe will likely devastate ATP Oil & Gas's operations as well. Two of its wells in the Gulf will be delayed into next year as a result, and it's uncertain what the regulatory landscape will look like when the moratorium is lifted.

CAPS member binve isn't sure ATP has hit bottom just yet, but thinks the downside risks at these levels seems a lot lower than the upside potential:

I think the management has made some smart long term strategic purchases. But their debt load is high and their stock ran up too far *way too fast* since this last correction. And now it has corrected back down way too fast. It is bouncing off very strong support.

Is this "the bottom" for ATGP? I have no idea. I just know that I like the risk/reward here for a bounce that should last awhile. And if it gets down to $6.00, I will like it even more.

Par for the course
Investors remain encouraged about the long-term potential of Spectrum Pharmaceuticals, both for Zevalin, its monoclonal antibody chemotherapy for non-Hodgkin's lymphoma, and for other drugs still under development. CAPS member jackflood thinks Spectrum will enjoy greater success as its portfolio candidates come up for regulatory approval:

no doubt management has enriched itself. that said, they have positioned the company in an extremely advantaged position. i feel that the present products, and the possibility of future fda approvals, present an extreely large upside for the company.

He's not alone; 99% of the CAPS members rating Spectrum have marked it to outperform the broad market averages. Add your opinion to the Spectrum Pharmaceuticals CAPS page, and let us know whether you think it covers the full range of possibilities.

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

Intel is a Motley Fool Inside Value pick. The Fool has created a covered strangle position on Intel. Motley Fool Options has recommended buying calls on Intel. Try any of our Foolish newsletter services today, free for 30 days.

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