Hm I think they changed the offer, because when I went through a week 1/2 ago I got two for $15 (including shipping). Ah yep...
>While supplies last, GitHub users can purchase special edition U2F Security Keys for $5 plus shipping and handling (regular price $18; 5,000 special edition keys available).
After the special keys are gone, all GitHub users are eligible for a 20% discount on U2F-certified YubiKeys, for a limited time.
>While supplies last, GitHub users can purchase special edition U2F Security Keys for $5 plus shipping and handling (regular price $18; 5,000 special edition keys available). After the special keys are gone, all GitHub users are eligible for a 20% discount on U2F-certified YubiKeys, for a limited time.