Just as we examine companies each week that may be rising past their fair value, we can also find companies potentially trading at bargain prices. While many investors would rather have nothing to do with companies tipping the scales at 52-week lows, I think it makes a lot of sense to determine whether the market has overreacted to the downside, just as we often do to the upside.

Here's a look at three fallen angels trading near their 52-week lows that could be worth buying.

Scotty, I need more power!
You've heard me push the importance of having necessity stocks in your portfolio in both good and bad times because they often supply dividend income as well as a level of stability not usually seen in most companies. That's why I think it's time to take electric utility Exelon (NYSE: EXC) out of the doghouse.

Exelon has been pressured by decade-low natural gas prices and just overall utility sector weakness in 2012. Why is Exelon continuing to head lower? Your guess is as good as mine! The company is set up in such a way that it'll make money whether the economy is growing or contracting, and its quarterly payouts have not dropped since 2001. Now yielding north of 5% and valued at just 10 times trailing-12-month earnings, I think you'd be foolish to pass up Exelon's strong cash flow.

Bio-Batman
Batman protected Gotham City against social deviants. Emergent BioSolutions (NYSE: EBS) is the biotech equivalent of Batman in that it protects our military against biotoxic substances like anthrax. Most everyone (including myself) assumed that the company's anthrax treatment, BioThrax, would provide only a temporary pop for the stock. The company has proved those naysayers wrong and predicted continued growth for BioThrax, in addition to signing a multiyear contract with the CDC.

Emergent's non-biodefense pipeline shouldn't be discounted either. The company, which is already profitable from BioThrax, has focused its attention on its BioSciences division, developing key partnerships that are expected to account for more than 20% of revenue in 2012. SBI-087, an autoimmune therapy targeted at rheumatoid arthritis and systemic lupus erythematosus, is being co-developed with Pfizer (NYSE: PFE). Emergent and Abbott Laboratories (NYSE: ABT) actually just ended an agreement on the development of TRU-016 for chronic lymphocytic leukemia and non-Hodgkin's lymphoma, but Emergent gets to keep all rights to the drug. Profitable and with a deep pipeline, Emergent looks like it could be your portfolio's Dark Knight.

Presto change-oh!
National Presto Industries (NYSE: NPK) has definitely had better weeks. The company, which manufactures small appliances, paid out a $1 annual dividend on top of a $5 special dividend this past week but, as Foolish colleague Matt Koppenheffer pointed out, the stock dropped a lot more than that. I'd suggest overlooking what seems like a selling overreaction and consider giving Presto another chance.

Its results over the past nine months aren't exactly pretty. Total sales fell 7%, while expenses rose 12% and net income fell 34%. If demand was weaker I would consider this a potential problem. But in this case costs are the main culprit with raw material costs and freight costs rising to such an extent that they squeezed margins. Those types of problems can be easily correctable within a quarter or two with a price hike and the introduction of new products. National Presto has a long history of taking care of its shareholders with exceptional dividends and is priced cheaply at just nine times trailing-12-month earnings.

Foolish roundup
Utilities, biotechs, and consumer goods -- sounds like the recipe for a balanced portfolio and just the right amount of dividend income and growth potential. I'm so confident these three names will bounce off their lows that I'm going to make a CAPScall of outperform on each one.

In the meantime, consider adding these potential winners to your free and personalized watchlist and get your own personal copy of our latest special report, "The Motley Fool's Top Stock for 2012," to see which company our chief investment officer has dubbed the "Costco of Latin America." Best of all, this report is completely free, so don't miss out!