Kiwirail Scenic is offering 20% off fares from Christchurch to Wellington (including ferry). The discounted adult fare is $127 each way, saving $32 off the normal price.
Sample booking screenshot. Similar to last year's deal where they were offering $99 tickets.
For bookings from now until Sunday, 28th August 2016. Travel between 23 September 2016 and 31 March 2017
Spotted in today's Dominion Post. Note: You won't see this discount if you use a VPN. NZ IP addresses only.