My employer asked for a quote for a couple hundred thousand of Yubikey devices and the price per unit was extremely close to the per unit price of the hardware when purchased on Amazon.
I can't convince anyone in my Enterprise that Yubico hardware is even worth a minute amount of attention, anymore.
Congratulations, Yubico.
I do have several YubiKeys for testing smart-card functionality in a MS AD environment. At least those are affordable
If you generated your PGP key on yubikey 4, BEWARE! It is vulnerable to latest attack:
https://www.yubico.com/support/security-advisories/ysa-2017-...