I have been using mine for about a year now and I also use a YubiKey PAM module to log in into my Ubuntu workstation.
If you search google a bit I am pretty sure you will find a discount code to get it even cheaper :)
In fact I finished that just this week, I'm considering using it full-time for some of my machines now.
The nice thing as far as I'm concerned is that unlike some other similar devices, all the specs for the OTP generation and all the software components are open-source.
Now to get two-factor auth working on my boxes... It seems there is a Python PAM module: https://github.com/Kami/advanced-yubico-pam-module
From the webpage:
* Non-intrusive. pam_usb doesn’t require any modifications of the USB storage device to work (no additional partitions required).
* USB Serial number, model and vendor verification.