Wyze[wyze.com] has Bo'er KN95 Disposable Face Masks (10 Count) for $19.99. Shipping is included.
Complies with GB 2626-2006 to meet KN95 standards, which is on the CDC list for "Use of respirators approved under standards used in other countries that are similar to NIOSH-approved N95 respirators."
Filters out particles and viruses in the air. It reduces the wearer's exposure to particles including small particle aerosols and large droplets.
Filters out at least 95% of airborne particles including small particle aerosols and large droplets (does not filter out oil-based aerosols).