An independent small pharmacist has asked you to source a small number $(20$ to $50)$ of $3M$ N$95$ masks at a reasonable price $($ $$1$ to $$2$ each$).3$M masks have better quality than others. N$95$ prevents at least $95\%$ of bacteria and viruses larger than $0\mathrm{.}3$ microns from getting in$.$ The pharmacist would like foldable masks without exhalation valve. Models $($N$95)9205+$ and $($KN$95)9502+$ or equivalent are acceptable.

a$.$ Search in North America for a good source. Provide the link to the product and price.

b$.$ Search in China for a good source. Provide the link to the product and price.