In Feb 2014, I did an analysis of Vitamin C costs. These calculations were at 6.21¥ per USD.
I had my son send me a bottle Costco brand vitamin C, 500 tablets, 1,000mg tablets. My cost, including shipping was $34 U$D.
I compared the cost of two domestic vitamin C products and two imported vitamin C products I found on Nan Ping Jie:
Costco 214¥ per bottle, cost per mg was 0.00007 U$D
Domestic A 108¥ per bottle, cost per mg was 0.01496 U$D
Domestic B 198¥ per bottle, cost per mg was 0.00674 U$D
Import A 239¥ per bottle, cost per mg was 0.00087 U$D
Import A 98¥ per bottle, cost per mg was 0.00350 U$D
Chinese labelling is not always clear. The size of the tablet will be clearly given but to find the amount of Vitamin C per tablet requires careful reading. Both domestic brands were 100 mg tablets but one contained only 11.8 mg 'C' per 100 mg tablet and the other 32 mg 'C' per 100 mg tablet.
Nearly all the vitamin C sold in the US originates in China.
Aspirin can be found in 50 and 100 mg tablets and the cost per mg is much cheaper than the US 325mg tablets.
In China Tylenol is hard to find and quite expensive. It also doesn't look right.
Full disclosure: One of the imported vitamin C product is well known to me. I brought a Taiwanese business guy, a Chinese scientist living in the US and a Vietnamese born pharma company owner, together to design, manufacture and distribute standardized TCM pills. Their products were to be exported to China. I found only their line of Western vitamins for sale.