We have been buying extra strong PG Tips British tea from Amazon because we think American tea is way too weak. 3 boxes of 80 were about $40 last time I bought them a few months ago. They’re now $80. Thankfully we discovered we can get an order of 6 for $60, but we have to wait until mid-February for the to arrive. Meanwhile, a single box of the same tea, which we’ll have to get in the mean time, is $20. Yes, a single box is less than a 3-count box order, but you still save if you buy 6 boxes. How does any of that make sense?
Yeah lots of “drop shipping” folks on Amazon, they buy a pallet of whatever it is from the same source as the top seller and then do some magic to get the “buy box” (the company that shows as default seller). Once they run that person out of business they are free to raise pricing until they no longer are winning the buy box again.
Amazon has also gotten bad with who it allows to sell on the site, and has been known to lump similar SKUs together, even ones from different sellers. This becomes especially troublesome when someone in the stack is selling counterfeit items.
All that is to say, pay attention to who you are buying from, and be on the lookout for counterfeit items.
EDIT - I don’t think this is the case here, but Amazon is also known to look at the users location and device and change prices accordingly. A great example of this is that sometimes a user buying from an Apple device (desktop or iPhone) will pay more than a user from a cheaper Android or Windows PC for the same item.