Update on online mask buying (possibly hoarding). No more ordering for now.
All bought on eBay (except for the first and last example) with fears of things getting worse and my friends and students lacking masks. Type of mask indicated, with cost per mask (including shipping and taxes).
Taiwan (pre-rationing) – proper masks – 6 元 each (40 total)
US (Made in China) – virtually useless dusk masks (lied that they were surgical) – 20 元 each [free after I complained, and I keep them] (200 total)
Poland (not quite surgical quality) – 30 元 each [10 元 each after I complained] (50 total)
Russia (very close to what we get from the pharmacies here, wrapped well, I didn’t complain) – 24 元 each (50 total)
US (high quality; better protection than local masks; super fast delivery) – 37.5 元 each [I know] (80 total)
US (N95; premium on 3M) – 180 元 each [ouch, but for personal protection in hot spots] (20 total).
Israel (N99/FFP3; premium for 3M) – 270 元 each [super paranoid purchase, but good product individually wrapped] (25 total).
UK (FFP3/N99, SHTF scenario in my mind) – 393 元 each [first purchase of masks, too impulsive, buyer beware] (10 total)
Lithuania (3M FFP2/N95) – 147 元 each (total 20)
Taiwan (kids masks; local online site). – 10 元 each (total 40). Somehow made it to my Taiwanese friend’s kids in China 
. No kids masks where he lives with his Taiwanese kids and wife.
Let me know if you have questions about shipping speed, but all were delivered within three days to three weeks.