You should never buy a used breast pump or share a breast pump.
Only FDA cleared, hospital-grade pumps should be used by more than one person. With the exception of hospital-grade pumps, the FDA considers breast pumps single-use devices. That means that a breast pump should only be used by one woman because there is no way to guarantee the pump can be cleaned and disinfected between uses by different women.
The money you may save by buying a used pump is not worth the health risks to you or your baby. Breast pumps that are reused by different mothers can carry infectious diseases, such as HIV or hepatitis.
Buying a used breast pump or sharing a breast pump may be a violation of the manufacturer’s warranty and you may not be able to get help from the manufacturer if you have a problem with the pump.