Source: Flickr user Kat R.  

Dividend stocks are the cornerstone of many well-run retirement portfolios -- that's a fact. The reason is that dividends act as a beacon to investors, inviting them to take a deeper look into a company whose business model is so sound it can pay out a percentage of its annual profits to its investors on a regular basis.

Further, dividends can provide a downside hedge in volatile and bear markets. Investors in dividend stocks tend to be oriented more toward the long term, which usually makes for less day trading and less volatility. Lastly, dividends can be reinvested, giving buyers a chance to compound gains over the long run. These payouts can mean the difference between simply retiring and living out your dream retirement.

With that in mind, let's have a look at three cheap dividend stocks you should consider buying right now.

1. Amgen (NASDAQ:AMGN)
If drug development pipelines are like 10,000-piece puzzles, after 10 years of finding the border pieces Amgen is finally at the point where the pieces in the middle are beginning to come together.

Source: Amgen, Flickr.

Following a decade where growth was relatively slow and Amgen relied on share buybacks to help drive EPS growth, the company is projected to deliver data on, or file new drug applications for, 10 late-stage products between 2014 and 2016. We've already seen this strategy for Amgen bear fruit, with Blincyto approved as a treatment for Philadelphia chromosome-negative relapsed/refractory B-precursor acute lymphoblastic leukemia in late 2014, and just last week AMG 416 delivering positive results in a head-to-head trial versus Sensipar in patients with secondary hyperparathyroidism who are receiving hemodialysis.

Among those catalysts, three in particular have my full and undivided attention: Kyprolis, Corlanor, and T-Vec (short for talimogene laherparepvec).

Source: Amgen, Flickr.

Kyprolis is the prized cancer drug inherited with the purchase of Onyx Pharmaceuticals, and Amgen is looking forward to a decision in 2015 as to whether it'll gain a lucrative label expansion as a second-line multiple myeloma therapy. Corlanor is Amgen's chronic heart failure drug, and it intrigues me because of the broad patient pool that it could potentially help. T-Vec might be the most interesting of all, as it's Amgen's attempt at an immunotherapeutic product for metastatic melanoma, and an approval could lead to numerous T-Vec drug combinations being tested.

In short, Amgen has a lot of near-term catalysts, and that bodes well for its long-term growth rate as well as its current 2% dividend yield. With a forward P/E of 15, it's not too late to give Amgen a closer look.

2. Teva Pharmaceutical (NYSE:TEVA)
Whereas Amgen is climbing out of its dormant growth period, concerns persist that hybrid drug developer Teva Pharmaceutical could be entering a challenging growth environment. The concerns relate to the coming patent exclusivity expiration of multiple sclerosis injection Copaxone, which accounts for nearly a fifth of Teva's revenue. Obviously seeing Copaxone lose sales to generic competition is going to sting both Teva's top- and bottom-line.

Source: Teva Pharmaceutical Industries, Facebook.

However, I suspect that the pessimism surrounding Teva may already be baked into its share price. You see, Teva is a rare drug developer; half its revenue is derived from generic drugs, while the other half comes from branded products. The advantage of hitting both ends of the drug supply spectrum is that Teva can enjoy the high margins associated with branded products, while also basking in the high volume and seemingly endless opportunity of generic products.

Source: Teva Pharmaceutical.

In Teva's latest quarterly results the company delivered strong growth for its branded oncology pipeline, as well as wakefulness drug Nuvigil whose sales climbed 38%. Although Teva's global generic revenue fell, this was mainly a function of the company exiting non-profitable markets and attempting to maximize its operational efficiency. Additionally, Teva is successfully converting existing users from a once-weekly dose of Copaxone to a three-times-per-week dose, thus extending the patent life of its blockbuster. 

Looking ahead, I see opportunities for Teva to make acquisitions to further diversify its branded-drug portfolio, while relying on the increasing number of exclusivity losses in the U.S. to drive growth in its generics division. With pharmacy-benefit managers and insurers looking for ways to help their members for the cheapest cost possible, I'd project the role that generics play may grow even more.

At just 11 times forward earnings Teva is beginning to look inexpensive. Tack on a 2.4% dividend yield as well (a dividend which doesn't grow with any rhyme or reason mind you), and you have all the makings of a potentially attractive cheap dividend stock.

3. National Oilwell Varco (NYSE:NOV)
Lastly, I'm once again going to contend that the oil service sector is a big source of cheap stocks and bountiful dividends.

Source: National Oilwell Varco, Facebook.

As you might have imagined, a drop in oil prices is to blame for the recent weakness in National Oilwell Varco, a supplier of equipment used in drilling rigs. As oil prices have fallen and some rigs have been idled there simply haven't been enough new contracts to go around. The fear is that persistent weakness in crude prices could do further damage to an already weak service contractor sector.

Source: National Oilwell Varco, Facebook.

However, National Oilwell Varco is a profitable monster! It finished 2014 with a backlog of $12.54 billion, or the equivalent revenue to take it roughly 15-16 months into the future without a slowdown from its current revenue reporting pace. Furthermore, as Foolish energy guru Tyler Crowe notes, National Oilwell Varco "has maintained an unlevered free cash flow margin greater than 10%" since 2006. This high FCF margin, as Crowe contends, gives the company incredible financial flexibility, and could even allow it to make accretive acquisitions if valuations within the sector dip low enough.

Ultimately, a bet on National Oilwell Varco is a bet on a long-term rise in energy demand. As emerging markets transform into industrialized nations, the demand for crude oil and natural gas should rise, lending credence to the idea that oil prices and National Oilwell Varco's workload should increase over time.

Currently valued at 16 times forward earnings the company may not appear exceptionally cheap, but taking into account its robust backlog, high margins, and delectable 3.4% dividend yield, this cheap dividend stock more than holds its keep.