SAVEWITHMAVEN
Just tested this on an adult 9 Day ticket which was $1099. After applying the coupon it came down to $999. Not sure how it applies to other tickets.
Source: https://www.youtube.com/watch?v=SamKYJjLD9w
Cycling Maven is a Melbourne-based cycling vlogger - check him out!
Its great fun to do the GVBR, you can even do it for FREE ,if you volunteer and ride.