We are very fortunate to have had a supply of N95 masks on hand due to our lung conditions prior to Covid, and used them very sparingly when we traveled home & throughout the summer. Circumstances allowed us to get a few more, and we are carefully using them as needed. We have asked for a few more, and we shall see.
In the meantime, I will say that the double masks are very nearly as effective if you make sure there are no gaps around the edges.

That said, I am looking for an on-line source for certified masks, and will share once I find one.

Please remember, when you hear stories of Covid after vaccine, millions of doses have been distributed, and only a handful of post-vaccine infections have been reported. That is what 94-95% effective means - there will still be a few cases. Compared to the flu vaccine (40-60%) or Shingrix (80%) that's stellar. And remember, they never report the details, the person could have had a condition making it more difficult to make antibodies.

@merpreb - N95 masks vary in comfort for longer term wear - some are nearly suffocating, the 3M ones (rare as hens' teeth) are very tolerable to me. Certified KN95 masks (NIOSH or OSHA or EU) are better, but you have to be more careful fitting them to your face for effectiveness. A couple of clues for anyone looking at N95 masks - the elastic always goes over the head, never around the ears. And it is not stapled to the mask because that pierces the protective fiber, though it may be stapled to the flange around the very edge, where the seal is.
Sue