Source: via Flickr.

New all-time highs are becoming an almost regular occurrence for the Dow Jones Industrial Average and S&P 500. For some companies this rally has led to an extended or frothy valuation. But others are still trading at potential bargain prices and are what we would call "value stocks."

Let's take a look at three so-called value stocks that could be worth buying right now.

1. Gilead Sciences (GILD -1.74%)
Is it wrong to keep pounding the table for more Gilead Sciences? If you read the same earnings report that I just read, I believe the answer is "No!"

Source: Gilead Sciences.

Last week Gilead announced its highly anticipated first-quarter results. For the quarter it generated $7.6 billion in revenue, up more than 50% from the $5 billion it produced in Q1 2014, as hepatitis C product revenue soared. As expected, revenue from hepatitis C treatment Sovaldi fell to $972 million from $2.3 billion year over year due to the introduction of HCV drug Harvoni. Harvoni, however, produced a ridiculous $3.6 billion in sales, putting it on pace to hit well over $14 billion for the full year. It's possible, even with discounting tied to its long-term pharmacy-benefit manager and insurer deals, that Harvoni could be the best-selling drug in the world in 2015. And let's not forget that HCV therapies have just begun to reach the approximately 180 million HCV patients worldwide, meaning this is a multidecade opportunity.

There were a number of other highlights, too. Stribild, the company's four-in-one HIV/AIDS pill, saw sales increase 66% from the prior-year quarter to $356 million. Stribild is now on pace to make $1.4 billion in revenue for the full year, and this figure is likely to continue rising. Complera/Eviplera has been strong as well, with $320 million in Q1 revenue, up from $251 million in the prior-year period.

Looking ahead, Gilead investors also have a lot to look forward to from its pipeline. New combination therapies involving Sovaldi and a number of potential liver disease cures, such as hepatitis B and nonalcoholic steatohepatitis, could be in the offing a few years down the road.

Trading at less than 10 times 2016's consensus EPS figure and sporting a PEG ratio of less than one (and paying a dividend!), this value stock is still worth considering as a smart long-term buy.

2. Allegiant Travel (ALGT -2.72%)
When push comes to shove, national airline Allegiant Air won't win any awards when it comes to top-notch customer service, and you're unlikely to find many frills.

However, Allegiant meets another important demand for travelers: affordability. Instead of trying to outdo major airlines in terms of routes, Allegiant dangles an extremely low ticket price in front of consumers and then uses optional fees to rake in high-margin revenue. Because a number of its fees are collected online or at airport kiosks without the need for an Allegiant agent, they end up being almost pure profit for the company.

Source: Allegiant via Facebook.

Allegiant's average fleet age is 22 years, so you won't find many modern luxuries on its older planes. But what Allegiant lacks in the latest plane technology it makes up for in upfront expenses, as the intermediate-aged used planes it purchases don't cost upwards of $250 million like a new 787-9 Dreamliner from Boeing. These cost savings, compounded with significantly lower fuel costs due to the drop in oil prices, create an almost utopian scenario for Allegiant's margins.

Wall Street currently projects Allegiant will bring in more than $17 in EPS by 2018, with revenue growing about 10%, putting the stock's forward P/E (in 2018) below 10 and its PEG ratio below one -- both indicative of a value stock. My suggestion would be to use this latest pullback as an opportunity to dip your toes into the water.

3. Toll Brothers (TOL -2.38%)
Homebuilders have generally been stuck in the mud for quite some time as fears about an inevitable interest rate hike from the Federal Reserve have kept investors at bay. Consumers have shown time and again that they're extremely sensitive to interest rate moves, lending to the idea that as the Fed begins raising rates, housing starts and sales will slow dramatically.

Source: Toll Brothers via Facebook.

However, there's a difference between rumors of a rate hike and an actual rate hike. Once the FOMC does begin raising the federal funds target to more modest levels, I expect prospective homeowners will realize they're still getting one heck of a good deal, considering where lending rates have been historically.

Toll Brothers is a unique homebuilder in that it focuses on luxury homes. The advantage here is that a more affluent audience grants the company greater resistance to interest rate fluctuations than that of its peers, which focus on consumers with less elastic budgets.

In the first quarter, which Toll reported back in February, its average price of homes delivered rose to $782,300 from $693,600, and it delivered 18% more units than in the prior-year quarter. Gross margin, unsurprisingly, rose to a robust 27.3%. Between rising home prices and the type of client Toll attracts, the company should continue growing for years to come.

Currently valued at 11 times Wall Street's 2017 EPS consensus estimate, and with a revenue growth rate of roughly 15%, Toll's PEG ratio of less than one really stands out. You may not be able to buy into Beverly Hills, but this value stock could allow you to get as rich as its residents.