According to the sources provided, Lipitor (atorvastatin) is a medication used to lower cholesterol levels and prevent heart disease. Lipitor is available as a brand-name drug and a generic drug.

The first source [1] provides information on the patent expiration of Lipitor. The patent for Lipitor expired in 2011, which allowed other pharmaceutical companies to produce generic versions of the drug. This means that Lipitor is now available as a generic drug, which is typically less expensive than the brand-name version.

The second source [2] provides a list of generic medications available at Walmart for a discounted price of $4 for a 30-day supply. Atorvastatin, the generic version of Lipitor, is included on this list. This suggests that Lipitor is available at Walmart at a lower cost than at other pharmacies.

The third source [3] reports on a promotion by Pfizer, the manufacturer of Lipitor, that offered the drug for free to eligible patients for a limited time. This promotion was an effort to maintain market share in the face of competition from generic versions of the drug. While this promotion is no longer available, it suggests that the cost of Lipitor may be higher than that of generic atorvastatin.

In conclusion, while Lipitor may not always be cheaper at Walmart, the generic version of the drug, atorvastatin, is available at Walmart for a discounted price of $4 for a 30-day supply [2]. It is important to note that prices may vary depending on location and other factors. Patients should consult with their healthcare provider and pharmacist to determine the most cost-effective option for their individual needs.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.goodrx.com/healthcare-access/pharmacies/the-walmart-4-generic-prescriptions-list
[3] https://www.npr.org/sections/health-shots/2012/09/12/160997059/how-cheap-can-lipitor-get-try-free