I've been shipping hundreds of thousands of masks to different institutions from China for the last 6 weeks - Universities, Government Agencies, Postal Companies, etc through my company ZipX.
Supply is a factor - the prices are ridiculous - but not the biggest limiting factor
The two main issues are
1. How do you trust the factory?
Unless you have worked with or vetted a factory for awhile how do you know the masks are actually rated at the level they say or that they will even deliver once they get the money?
So so many websites and factories can supposedly sell you millions of cheap BFE 99% or N95 masks yet did not even exist 2 weeks ago. Certificates can be photoshopped. Most of the countries that manufacture these days have no legal recourse if they scam you. We have local offices in all the countries we import from, did multiple visits in person, tested out larger and larger sample orders and they still tried to scam us by switching out the masks for used ones 3 weeks in.
2. How you do you deliver it?
The customs laws are changing all the time. Unless you have contacts there to check the current status you may have information that's a week out of date. India just banned the export of masks a few days ago. The Shanghai gateway blocks 3-ply masks to Hong Kong but the Shenzhen gateway doesn't.
Also flight space is extremely limited. You have to have dedicated space booked or a contact for large space like these supplies need. Your average person isn't going to get 1,000,000 of anything on a cargo plane within a week.
Flexport has been around long enough and has local offices and contacts to deal with these.