For regulatory reasons, US drug list prices are completely detached from the actual price you end up paying (assuming you do a bit of research). See e.g. https://www.goodrx.com/hydroxychloroquine ($20 for 60x200mg)

Quinine course used to cost around 1.5 RMBs in 1998.

Managed to catch malaria in Hebei out of all places, during my first trips to China with my father.

Right, the only medication I sometimes bring from the US now is acetaminophen/paracetamol because it's the only one I've found that's much cheaper there. The rest are probably cheaper in Germany so I would just go there if I needed them.

Indeed. Another example: https://twitter.com/jawj/status/1199026735980990465

For Kenya, it works out as 0.3 USD/tablet for HCQS

I believe its around $30 in the US at Ralphs or Costco

It is, but in recent years it was much higher because of "shortages" (actually just lack of competition after one of the main suppliers got busted by USDA for poor quality control).