You can absolutely sell these. Google may ask you not to, but that does not inhibit you from selling them and they work fine for the next buyer. This is pretty awesome, Go Bitcoins!
Even so it happens. I bought my pair since I couldn't get a pair any other way. Even at this years Google IO you couldn't sign up to get a pair. I think it would have been interesting to buy them with Bitcoin though but in my case I paid cold hard cash for mine.