Hello,
Yeah, that price is definitely not right, I would ask the same questions.
The problem is, Microsoft has no way of knowing who these sellers are and what they sell you.
But since you already used it, there's a way to check real quick.
Can you please type cmd in the search on the taskbar and hit enter to launch command prompt, then run the following command:
slmgr /dlv
Then share a screenshot please. Thanks!