Right now, I don't know how legitimate it is and it is Amazon but there is this listing from one of Amazon's deal companies (an acquisition called woot):

https://www.amazon.com/dp/B08J1THV9G

$27 for 440 n95 aura masks.

Doubt this lasts, seems like a mistake or maybe there's something going on there. Probably don't have a distant expiration date. Also might want to consider the elastic on them may have been subjected to stresses from bad storage but even if they only last one wear they're so cheap you're still saving money. And you can always buy covered elastic and staple it yourself to the masks in place of the ones they come with. For this price it would be worth it I think.

So hypothetically this should probably be more reliable than the third party sellers on amazon. Probably surplus from somewhere, probably not brand new but hopefully still good.