Pegasys is used to treat Hepatitis B. The generic version is called Peginterferon alfa-2a. The average Pegasys cash price is about $1,024.83 for a supply of Solution 180 MCG/0.5ML 1 Syringe. You can reduce your Pegasys cost by up to 75% with our free Pegasys discount card. Bring it to a participating pharmacy near you to save on your prescription medication.