If you want to try for one of the 5,000 $5 Yubikey with everyone else currently killing the server...

1) sign in with github at: https://www.yubico.com/github-special-offer/

2) buy now: https://www.yubico.com/github-special-offer/github-yubikey-s...

3) checkout: https://www.yubico.com/checkout/

Once you complete one step successfully you should be able to skip to the next. Good luck vs. the 504's!