Eru, I got emailed today as a 'previous booker of Wagner tickets at ROH'. Try them. They'll all be gone before you can say 'Hagen der Grimme'.
Thanks for putting this on the board, martle. I'm another who wouldn't have known about it otherwise; and they are, as you predicted, rapidly disappearing despite the fact that you can't book them (or even read about them) via the ROH website and they're only selling them by the cycle. I've bought mine from the dwindling stock that was still available this afternoon. Now, I've just got to arrange time off work, try for a cheap train ticket and see which of my Southern friends can put me up for the duration.