Need 9 licences for windows 10 Pro - Where should I Purchase these?

Hello everyone, guys
Hope you all are fine there is a certain problem which I am facing nowadays which I had explained down.

I need to upgrade the 9 clients which I have from windowsill to windows 10 pro. Mostly the one thing I will be doing destructive upgrades on these systems by this I can do a clean install of Windows 10.
I have tried Online but there I find pricing anywhere from $28.00 to $199 (Price from MS direct). Since we don’t need a volume license I typically go to CDW or Newegg or direct to MS for this type of purchase but I’m intrigued by these lower price offerings from companies who may or may not be legit. Here are a few specific questions around this.

  • Has anyone used these inexpensive licenses? Any pitfalls to be aware of?

Thankful to all of you for giving me a time

Hello @JamesB

Microsoft site link