We sell them for various things at the paint store. IE: Dust, lacquer spraying, etc. Take a look on ebay and Amazon. There are some over $100 for 2 masks which used to cost $5 for a 2 pack.
I will say some of the links I clicked on at Amazon would not load to my cart. Looks like Amazon is implementing the block. We sell the N95, P95 and R95 and none are available anywhere. P95 and R95 are N95 rated plus oil droplets whereas N95 will not protect against "Droplets of oil".
Digerati is correct about the fit, if you buy an adult mask for a child it is as ineffective as having nothing on against a virus or fumes. If you can find masks, make sure they fit perfectly.
I for one am hoping for the positive side of things with corona, as the influenza virus kills 25,000-69000 people every year. However, it is never a bad thing to be prepared.