There are people like us that are obsessed with the products they use, so there is a black market for discontinued products
Same happened when they discontinued the VX Nano for the Anywhere MX, New ones were instantly ~$200, now they are extinct
Spare parts seem affordable tho, I might restore all my mouses some time, Nano VX and the G9X share the same scroll, interestingly
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One sad aspect of buying spare mouses is, they might have defects that you only notice when you start really using them
I used to keep a spare Anywhere MX, my last spare had unique wireless issues for example, left the keypress randomly at times
So you might want to thoroughly check the mice you get, to not discover these kind of issues in the future (I know G9X isn't wireless, yet there are countless issues with these Logitech mouse's, they certainly don't deserve our devotion, but the competition is obviously worse)