We do not have a consistent source for finding retail drug price information.

Use Bloomberg (see access details) to find wholesale acquisitions costs.

• Type BI PHRM DEX and press the green <GO> key and then search for a specific drug.
• Once you are in a drug record, use the Pricing tab.  

See data from the Centers for Medicare & Medicaid Services:

• Prescription Drug Plan Formulary, Pharmacy Network, and Pricing Information Files 
• Medicare Provider Utilization and Payment Data: Part D Prescriber - includes "total drug cost"

Go to the International Medical Products Price Guide.

Also see the World Health Organization's Medicine Price Information Sources.