There’s a third-party seller on Amazon selling 50 face masks for around $16 with quick delivery. (affiliate links below)
This seller has multiple listings with basically the same product; the $16 price-point is their lowest. They have hundreds of reviews in the 3.5-4 range, so it looks like they’ll actually deliver.
(If you can wait a little, here’s one for a few dollars less, but it might not come until July 15th.)
