alt Hacker Newslabs don't certify that mask is more effective per dollar compared to usual air filters.
hence extra research by Corsi and Rosenthal is needed. After they will do the measurements they can be declared as inventors of p100 masks, that will be known as Rosenthal-Corsi masks
The p100 masks are already certified so you can shop based on cost. Filters + fans are not certified so you have to know something more to understand what you are getting